Metal-doped nickel oxide active materials

ABSTRACT

A primary battery includes a cathode having an alkali-deficient nickel oxide including metals such as Ca, Mg, Al, Co, Y, Mn, and/or non-metals such as B, Si, Ge, or a combination of metal and/or non-metal atoms; a combination of metal atoms; an anode; a separator between the cathode and the anode; and an alkaline electrolyte.

TECHNICAL FIELD

This disclosure relates to cathode active materials, and moreparticularly to metal-doped nickel (IV)-containing cathode activematerials.

BACKGROUND

Batteries, such as alkaline batteries, are commonly used as electricalenergy sources. Generally, a battery contains a negative electrode(anode) and a positive electrode (cathode). The negative electrodecontains an electroactive material (such as zinc particles) that can beoxidized; and the positive electrode contains an electroactive material(such as manganese dioxide) that can be reduced. The active material ofthe negative electrode is capable of reducing the active material of thepositive electrode. In order to prevent direct reaction of the activematerial of the negative electrode and the active material of thepositive electrode, the electrodes are mechanically and electricallyisolated from each other by an ion-permeable separator.

When a battery is used as an electrical energy source for a device, suchas a cellular telephone, electrical contact is made to the electrodes,allowing electrons to flow through the device and permitting theoxidation and reduction reactions to occur at the respective electrodesto provide electrical power. An electrolyte solution in contact with theelectrodes contains ions that diffuse through the separator between theelectrodes to maintain electrical charge balance throughout the batteryduring discharge.

SUMMARY

This disclosure relates to high-capacity primary alkaline batteriesincluding cathodes that include a layered nickel oxide with Ni having anaverage oxidation state greater than about +3.25 (e.g., greater thanabout +3.5, or greater than about +3.75) with one or more metal ions atleast partially substituting for Ni ions in the crystal lattice (i.e.,in solid solution) and an oxidation resistant graphite; an anodeincluding metallic zinc or zinc alloy particles (e.g., very fine zincparticles (i.e., −325 mesh)); an oxidation-resistant separator; and analkaline electrolyte solution.

In one aspect, the disclosure features a battery including a cathodecomprising an oxide having a formula A_(x)Ni_(1-y-z-w)Co_(y)M^(a) _(z)M^(b) _(w)O₂; an anode; a separator between the cathode and the anode;and an alkaline electrolyte, wherein A is an alkali metal, M^(a) is ametal dopant, M^(b) is a non-metal dopant, 0≦x≦0.2, w is 0 or 0≦w≦0.02and 0.02≦y+z≦0.25.

In another aspect, the disclosure features a cathode including a cathodeactive material having the formula A_(x)Ni_(1-y-z-w)Co_(y)M^(a)_(z)M^(b) _(w)O₂, where A is an alkali metal, M^(a) is a metal dopant,M^(b) is a non-metal dopant, 0≦x≦0.2, w is 0, or 0≦w≦0.02 and0.02≦y+z≦0.25.

In yet another aspect, the disclosure features a battery including thecathode of claim 25, an anode including zinc or zinc alloy particles, analkaline electrolyte solution, and a separator.

Embodiments of the battery may include one or more of the followingfeatures.

In some embodiments, x is less than 0.1, 0.02≦y≦0.15 (e.g., y is 0),0.02≦z≦0.08 (e.g., z is 0), and/or 0≦w≦0.02 (e.g., w is 0).

In some embodiments, the alkali metal is selected from the groupconsisting of Li, Na, K, Cs, Rb, and any combination thereof. M^(a) canbe selected from the group consisting of Ca, Mg, Al, Y, Mn, and anycombination thereof. M^(b) can be selected from the group consisting ofB, Si, Ge, or a combination thereof.

In some embodiments, the oxide further includes protons. For example,the oxide can further include protons at a stoichiometric ratio ofbetween 0.02 and 0.2 relative to total nickel and metal dopants. In someembodiments, the oxide can include Li_(x)Ni_(1-y)Co_(y)O₂,Li_(x)Ni_(1-z)Ca_(z)O₂, Li_(x)Ni_(1-y-z)Co_(y)Ca_(z)O₂,Li_(x)Ni_(1-z)Mg_(z)O₂, Li_(x)Ni_(1-y-z)Co_(y)Mg_(z)O₂,Li_(x)Ni_(1-z)Al_(z)O₂, and Li_(x)Ni_(1-y-z)Co_(y)Al_(z)O₂,Li_(x)Ni_(1-z)(Mg, Al)_(z)O₂, Li_(x)Ni_(1-y-z)Co_(y)(Mg, Al)_(z)O₂,Li_(x)Ni_(1-z)Y_(z)O₂, Li_(x)Ni_(1-y-z)Co_(y)Y_(z)O₂,Li_(x)Ni_(1-z)Mn_(z)O₂, and/or Li_(x)Ni_(1-y-z)Co_(y)Mn_(z)O₂. The oxidecan include Ni having an average oxidation state of greater than +3.25.

In some embodiments, the anode includes zinc or a zinc alloy. Theelectrolyte can include lithium hydroxide, sodium hydroxide, orpotassium hydroxide.

In some embodiments, the oxide has a low-rate capacity of at least 350mAh/g after storing for 24 hours at 25° C. The oxide can have a low ratecapacity of at least 340 bmAh/g after storing for one week at 25° C. Theoxide can have a low rate capacity of at least 300 mAh/g after storingfor one week at 45° C.

In some embodiments, the battery has a capacity retention of at least 95percent after storing for one week at 25° C. In some embodiments, thebattery has a capacity retention of at least 85 percent after storingfor one week at 45° C. The oxide can have an open circuit voltage offrom 1.75 to 1.85 V. The oxide can have an oxygen evolution afterstoring for three weeks at 25° C. of less than 4 cm³/g.

Embodiments of the battery may include one or more of the followingadvantages.

The battery can have an average closed circuit voltage of less thanabout 1.65 V (e.g., greater than about 1.45 V and/or less than about 1.7V), and can be compatible with devices designed for use withconventional alkaline batteries that include EMD-zinc and nickeloxyhydroxide-zinc. The alkaline battery can have a significantly greatergravimetric specific capacity when compared to commercial primaryalkaline batteries that include EMD-zinc and nickel oxyhydroxide-zinc.For example, the alkaline battery can include greater than about 325mAh/g (e.g., greater than about 350 mAh/g, greater than about 375 mAh/g,greater than about 425 mAh/g, or greater than about 450 mAh/g) whendischarged at relative low rates (e.g., <C/30) to a 0.8 V cutoffvoltage. The battery can have a better high-rate (e.g., >C/3)performance and comparable or greater capacity retention after storageat ambient room temperature and elevated temperatures, when compared tocommercial primary alkaline batteries.

In some embodiments, primary alkaline batteries having cathodes thatinclude a metal-doped Ni(IV)-containing active material can havedecreased internal gas pressure after storage compared to batteries thatinclude an undoped Ni(IV)-containing active material. Metal-doping candecrease generation of oxygen gas from decomposition of alkalineelectrolyte by Ni(IV)-containing active materials during storage atambient room temperature and/or at elevated temperatures.

The details of one or more embodiments of the invention are set forth inthe accompanying drawings and the description below. Other features,objects, and advantages of the invention will be apparent from thedescription and drawings, and from the claims.

DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic side sectional view of an alkaline primary roundcell/battery.

FIG. 2 is a plot depicting the Ni-rich portion of the ternarycomposition diagram for Li—Ni—Co—Mg and Li—Ni—Co—Al oxide systems,indicating the compositions of 25 metal-doped lithium nickel oxides,which are precursors to the corresponding delithiated metal-doped nickel(IV) oxides.

FIG. 3 is a plot depicting an overlay of the x-ray powder diffractionpatterns for cobalt, and cobalt and magnesium-doped lithium nickel oxidecompositions, and undoped lithium nickel oxide, measured using Cu Kαradiation and scanned between 17 and 46 degrees 2θ.

FIG. 4 is a plot depicting an overlay of the x-ray powder diffractionpatterns for cobalt, and cobalt and aluminum-doped lithium nickel oxidecompositions, and undoped lithium nickel oxide, measured using Cu Kαradiation and scanned between 17 and 46 degrees 2θ.

FIG. 5 includes SEM images showing representative morphologies andcrystallite sizes for selected metal-doped lithium nickel oxide powders:(a) undoped lithium nickel oxide, LiNiO₂; (b) magnesium-doped lithiumnickel oxide, LiNi_(0.96)Mg_(0.04)O₂; (c) aluminum-doped lithium nickeloxide, LiNi_(0.96)Al_(0.04)O₂; (d) cobalt and magnesium-doped lithiumnickel oxide, Li(Ni_(0.92)Co_(0.04)Mg_(0.04))O₂; and (e) cobalt-dopedlithium nickel oxide, LiNi_(0.92)Co_(0.08)O₂. Magnification for allcases is 10,000×.

FIG. 6 is a plot depicting an overlay of the voltage profile curves foralkaline button cells with cathodes including delithiated metal-dopednickel(IV) oxides: (a) Li_(x)Ni_(0.88)Co_(0.06)Mg_(0.06)O₂; (b)Li_(x)Ni_(0.88)Co_(0.08)Mg_(0.04)O₂; (c)Li_(x)Ni_(0.88)Co_(0.10)Mg_(0.02)O₂; and (d) Li_(x)Ni_(0.88)Co_(0.12)O₂,discharged at a nominal low rate (i.e., 7.5 mA/g) to a 0.8 V cutoffvoltage.

FIG. 7 is a plot depicting an overlay of the voltage profile curves foralkaline button cells with cathodes including delithiated metal-dopednickel(IV) oxides: (a) Li_(x)Ni_(0.88)Co_(0.04)Al_(0.08)O₂; (b)Li_(x)Ni_(0.88)Co_(0.06)Al_(0.06)O₂; (c)Li_(x)Ni_(0.88)Co_(0.08)Al_(0.04)O₂; (d)Li_(x)Ni_(0.88)Co_(0.10)Al_(0.02)O₂; and (e) Li_(x)Ni_(0.88)Co_(0.12)O₂discharged at a nominal low rate (i.e., 7.5 mA/g) to a 0.8 V cutoffvoltage.

FIG. 8 is a plot depicting a comparison of discharge capacities foralkaline button cells containing delithiated undoped nickel (IV) oxideand the delithiated metal-doped nickel (IV) oxides that wereacid-treated for either 40 hours or 20 hours and discharged at a nominallow-rate (i.e., 7.5 mA/g) to a 0.8 V cutoff voltage.

FIG. 9 is a plot depicting a comparison of energy retention values foralkaline button cells containing delithiated metal-doped nickel (IV)oxides that were acid-treated for either 40 hours or 20 hours, andstored at 45° C. for 1 week before discharge, versus the correspondinginitial OCV values.

FIG. 10 is a plot depicting a comparison of discharge curves foralkaline button cells with cathodes including: (a) delithiated cobaltand aluminum-doped nickel(IV) oxide,Li_(x)Ni_(0.80)Co_(0.15)Al_(0.05)O₂; (b) delithiated cobalt, aluminum,and boron-doped nickel(IV) oxide,Li_(x)Ni_(0.791)Co_(0.149)Al_(0.049)B_(0.01)O₂; (c) delithiated undopednickel(IV) oxide, Li_(x)NiO₂; and (d) electrolytic manganese dioxide(EMD), all discharged at a nominal low rate (i.e., 9.5 mA/g) to a 0.8 Vcutoff voltage.

Like reference symbols in the various drawings indicate like elements.

DETAILED DESCRIPTION

Referring to FIG. 1, a battery 10 includes a cylindrical housing 18, acathode 12 in the housing, an anode 14 in the housing, and a separator16 between the cathode and the anode. Battery 10 also includes a currentcollector 20, a seal 22, and a metal top cap 24, which serves as thenegative terminal for the battery. Cathode 12 is in contact with housing18, and the positive terminal of battery 10 is at the opposite end ofbattery 10 from the negative terminal. An electrolyte solution, e.g., analkaline solution, is dispersed throughout battery 10.

Cathode 12 can include an electrochemically active material having adoped alkali-deficient nickel oxide that optionally includes protons, anelectrically conductive additive, and optionally a binder.

An undoped alkali-deficient nickel oxide can be an alkali-deficientnickel oxide having a generic formula A_(x)NiO₂, where “A” is an alkalimetal ion, and x is less than 1 (e.g., 0≦x≦0.2). In some embodiments, xis between about 0.06 and 0.07. In some embodiments, x is as small aspossible to maximize an amount of Ni(IV) in a given alkali-deficientnickel oxide. The undoped alkali-deficient nickel oxide can have adeficiency of alkali metals compared to a nominally stoichiometriccompound having a generic formula of ANiO₂. The alkali-deficient nickeloxide can contain defects in the crystal lattice, for example, in thecase where the alkali metal has deintercalated or leached out of thecrystal lattice. In some embodiments, Ni ions can partially occupyinterlayer alkali metal sites in the crystal lattice. In someembodiments, Ni ions can be partially absent from nickel sites in thecrystal lattice, thereby creating vacancies at nickel sites. In someembodiments, the alkali metal includes Li, Na, K, Cs, and/or Rb.

In some embodiments, the alkali-deficient nickel oxide can be doped witha dopant metal, such as Co, Mg, Al, Ca, Mn, and/or Y. The metal-dopedalkali-deficient nickel oxide can have a general formula ofA_(x)Ni_(1-y-z)Co_(y)M^(a) _(z)O₂, where A is an alkali metal, M^(a) isa dopant metal such as Mg, Al, Ca, Mn, and/or Y, 0≦x≦0.15, and0.02≦y+z≦0.25. M^(a) can be a single metal or a mixture of metals. Inthe metal-doped alkali-deficient nickel oxide, Co can be present orabsent, and Mg, Al, Ca, Mn, and/or Y can be present or absent; providedthat at least one of Co, or an element selected from Mg, Al, Ca, Mn,and/or Y is present in the alkali-deficient metal-doped nickel oxide.For example, the metal-doped alkali-deficient nickel oxide can have anominal formula Li_(0.12)Ni_(0.92)Co_(0.08)O₂. In some embodiments, themetal-doped alkali-deficient nickel oxide can have a formula ofLi_(x)Ni_(1-y)Co_(y)O₂, Li_(x)Ni_(1-z)Mg_(z)O₂,Li_(x)Ni_(1-y-z)Co_(y)Mg_(z)O₂, Li_(x)Ni_(1-y-z)Co_(y)Al_(z)O₂,Li_(x)Ni_(1-z)(Mg, Al)_(z)O₂, Li_(x)Ni_(1-y-z)Co_(y)(Mg, Al)_(z)O₂,Li_(x)Ni_(1-z)Ca_(z)O₂, Li_(x)Ni_(1-y-z)Co_(y)Ca_(z)O₂,Li_(x)Ni_(1-z)Y_(z)O₂, Li_(x)Ni_(1-y-z)Co_(y)Y_(z)O₂,Li_(x)Ni_(1-z)Mn_(z)O₂ or Li_(x)Ni_(1-y-z)Co_(y)Mn_(z)O₂. The dopant(e.g., Co, Mg, Al, Ca, Mn, and/or Y) can substitute for Ni ions and/orpartially substitute for alkali metal ions in the alkali metal sitesbetween the nickel oxygen layers in the nickel oxide crystal lattice.

In some embodiments, the alkali-deficient nickel oxide can be doped withboth a non-metal dopant, such as boron (B), silicon (Si) or germanium(Ge), and a metal dopant, such as Co, Mg, Al, Ca, Mn, and/or Y. Themetal and non-metal doped alkali-deficient nickel oxide can have ageneral formula of A_(x)Ni_(1-y-z-w)Co_(y)M^(a) _(z)M^(b) _(w)O₂, whereA is an alkali metal, M^(a) is a metal dopant such as Mg, Al, Ca, Mn,and/or Y, 0≦x≦0.2, and 0.02≦y+z≦0.25, and M^(b) is a non-metal dopantsuch as B, Si, and/or Ge and 0≦w≦0.02. In some embodiments, x<1 and(y+z)<0.2; or x<1, 0.01≦y≦0.2, and 0.01≦z≦0.2. For example, acombination of metal and non-metal doped alkali-deficient nickel oxidecan have a formula of Li_(0.1)Ni_(0.79)Co_(0.15)Al_(0.05)B_(0.01)O₂.

In some embodiments, in a doped alkali-deficient nickel oxide having aformula of A_(x)Ni_(1-y-z)Co_(y)M^(a) _(z)O₂ orA_(x)Ni_(1-y-z-w)Co_(y)M^(a) _(z)M^(b) _(w)O₂, x is less than or equalto 0.2 (e.g., less than or equal to 0.15, less than or equal to 0.12,less than or equal to 0.1, less than or equal to 0.08, less than orequal to 0.05, or less than or equal to 0.03) and/or greater than orequal to 0 (e.g., greater than or equal to 0.03, greater than or equalto 0.05, greater than or equal 0.08, greater than or equal to 0.1,greater than or equal to 0.12, or greater than or equal to 0.15). Insome embodiments, to enhance discharge performance, x is less than 0.3.In some embodiments, at least one of y or z is greater than 0. As anexample, y+z is greater than 0 (e.g., greater than or equal to 0.02,greater than or equal to 0.04, greater than or equal to 0.08, greaterthan or equal to 0.1, greater than or equal to 0.15, greater than orequal to 0.2, or greater than or equal to 0.22) and/or less than orequal to 0.25 (e.g., less than or equal to 0.22, less than or equal to0.2, less than or equal to 0.15, less than or equal to 0.1, less than orequal to 0.08, less than or equal to 0.04, or less than or equal to0.02). In some embodiments, y is greater than or equal to 0 (e.g.,greater than or equal to 0.02, greater than or equal to 0.04, greaterthan or equal to 0.08, greater than or equal to 0.1, greater than orequal to 0.12) and/or less than or equal to 0.2 (e.g., less than orequal to 0.15, less than or equal to 0.12, less than or equal to 0.1,less than or equal to 0.08, or less than or equal to 0.04). In someembodiments, z is greater than or equal to 0 (e.g., greater than orequal to 0.02, greater than or equal to 0.03, greater than or equal to0.04, greater than or equal to 0.05, greater than or equal to 0.06, orgreater than or equal to 0.07) and/or less than or equal to 0.1 (e.g.,less than or equal to 0.08, less than or equal to 0.07, less than orequal to 0.06, less than or equal to 0.05, less than or equal to 0.04,or less than or equal to 0.03). In some embodiments, w is greater thanor equal to 0 (e.g., greater than or equal to 0.005, greater than orequal to 0.01, or greater than or equal to 0.015) and/or less than orequal to 0.02 (less than or equal to 0.015, less than or equal to 0.01,or less than or equal to 0.005).

In some embodiments, when a doped alkali-deficient nickel oxide hasthree dopants (e.g., two metal dopants and a non-metal dopant, twonon-metal dopants and a metal dopant, three metal dopants, threenon-metal dopants), the ratio for the three dopants can be, for example,1:1:1; 2:1:1; 2:2:1; 3:1:1; 3:2:1; 4:1:1; 4:3:3; 5:1:1; 5:2:1; 5:3:2;5:4:1; or 6:3:1. As an example, a Co:M^(b) ₁:M^(b) ₂ ratio can be 1:1:1;2:1:1; 2:2:1; 3:1:1; 3:2:1; 4:1:1; 4:3:3; 5:1:1; 5:2:1; 5:3:2; 5:4:1; or6:3:1.

The nickel in an alkali-deficient nickel oxide can have multipleoxidation states. For example, the nickel can have an average positiveoxidation state of greater than 3 (e.g., greater than 3.25, greater than3.5, or greater than 3.8) and/or less than or equal to 4 (less than 3.8,less than 3.5, less than 3.25, or less than 3.2). The nickel of thealkali-deficient nickel oxide can have a higher average oxidation statethan the nickel in a corresponding stoichiometric precursor alkalinickel oxide, prior to removal of alkali metal cation A. In someembodiments, the average oxidation state of the nickel in thealkali-deficient nickel oxide can be 0.3 greater (e.g., 0.5 greater, 0.8greater, or 0.9 greater) than the average oxidation state of the nickelin the corresponding stoichiometric precursor alkali nickel oxide.

The alkali-deficient nickel oxide including nickel having an averagepositive oxidation state of greater than 3, can have a layeredstructure; a spinel-type structure or can include a physical mixture orcomposite of layered and spinel-type structures, as well as otherrelated crystal structures. As an example, a lithium deficientnickel(IV) oxide, Li_(x)NiO₂, prepared by delithiation of a layeredLiNiO₂, can have either a layered structure related to that of thelayered precursor LiNiO₂ or a spinel-type structure, depending on thestoichiometry and/or heat treatment conditions.

In some embodiments, the alkali-deficient nickel oxides can have alayered crystal structure with alkali metal ions located in interlayerlattice sites located between the nickel-oxygen layers. Thealkali-deficient nickel oxides can have defects where alkali metal ionshave been extracted. In some embodiments, the alkali metal ions can bepartially replaced by protons in the crystal lattice. The interlayerspacing distance can be either maintained or changed after oxidativede-intercalation of alkali metal ions, intercalation of protons, and/oralkali metal ion/proton exchange. In some embodiments, the interlayerspacing can increase due to substitution by alkali ions having largerionic radii. For example, the interlayer spacing can increase when Liions are substituted by larger potassium (K) ions, anions, and/or watermolecules. In some embodiments, the interlayer spacing inalkali-deficient nickel oxides can increase due to increasedelectrostatic repulsion between the oxygen-containing layers afteralkali ion removal.

The metal-doped, non-metal-doped, and undoped alkali-deficient nickeloxides can be characterized by measurement of their x-ray powderdiffraction patterns, elemental compositions, and average particlesizes. In some embodiments, crystal lattice parameters of doped orundoped alkali-deficient nickel oxide and corresponding stoichiometricprecursors can be determined from powder X-ray diffraction (“XRD”)patterns. For example, X-ray powder diffraction patterns can be measuredwith an X-ray diffractometer (e.g., Bruker D-8 Advance X-raydiffractometer, Rigaku Miniflex diffractometer) using Cu K_(α) or CrK_(α) radiation by standard methods described, for example, by B. D.Cullity and S. R. Stock (Elements of X-ray Diffraction, 3^(rd) ed., NewYork: Prentice Hall, 2001). The unit cell parameters can be determinedby Rietveld refinement of the powder diffraction data. The X-raycrystallite size also can be determined by analysis of peak broadeningin a powder diffraction pattern of a sample containing an internal Sistandard using the single-peak Scherrer method or the Warren-Averbachmethod as discussed in detail, for example, by H. P. Klug and L. E.Alexander (X-ray Diffraction Procedures for Polycrystalline andAmorphous Materials, New York: Wiley, 1974, 618-694). In someembodiments, a layered, metal-doped lithium-deficient nickel oxide canhave a formula of Li_(x)Ni_(1-y-z)Co_(y)M^(a) _(z)O₂ orLi_(x)Ni_(1-y-z-w)Co_(y)M^(a) _(z)M^(b) _(w)O₂, can have an X-raydiffraction pattern indicating that interlayer spacing has changedrelatively little compared to undoped LiNiO₂. For example, the 003Miller index line at the approximate diffraction angle of 2θ=18.79° canremain almost at the same angle while other Miller index (e.g., hk0)lines can show a larger shift, indicating a relatively minor change inthe a and/or b unit cell parameters axis of the lattice. The extent ofstructural distortion also can depend on the average nickel oxidationstate, the site occupancy of the lithium ions and protons, as well astotal lithium ion/proton content.

In some embodiments, the mean particle size and size distribution for aalkali-deficient nickel oxide and the corresponding precursor alkalinickel oxide can be determined with a laser diffraction particle sizeanalyzer (e.g., a SympaTec Helos particle size analyzer equipped with aRodos dry powder dispersing unit) using algorithms based on Fraunhoferor Mie theory to compute the volume distribution of particle sizes andmean particle sizes. Particle size distribution and volume distributioncalculations are described, for example, in M. Puckhaber and S. Rothele(Powder Handling & Processing, 1999, 11(1), 91-95 and European CementMagazine, 2000, 18-21). In some embodiments, the alkali nickel oxideprecursor can include an agglomerate or a sintered aggregate (i.e.,secondary particles) composed of much smaller primary particles. Suchagglomerates and aggregates are readily measured using the particle sizeanalyzer. In some embodiments, scanning electron microscopy (“SEM”) canbe used to determine the morphology and average particle sizes ofparticles of a nickel oxide.

In some embodiments, the content of the nickel, metal dopants, non-metaldopants, and alkali metals in doped and undoped alkali-deficient nickeloxides can be determined by, for example, inductively coupled plasmaatomic emission spectroscopy (“ICP-AE”) and/or atomic absorptionspectroscopy (“AA”) using standard methods as described, for example, byJ. R. Dean (Practical Inductively Coupled Plasma Spectroscopy,Chichester, England: Wiley, 2005, 65-87) and B. Welz and M. B. Sperling(Atomic Absorption Spectrometry, 3^(rd) ed., Weinheim, Germany: WileyVCH, 1999, 221-294). For example, ICP-AE spectroscopy measurements canbe performed using a Thermo Electron Corporation IRIS intrepid II XSPICP with Cetac ASX-510 autosampler attachment. For some nickel oxidesamples including lithium and nickel, ICP-AE analysis can be performedseparately for Li (λ=670.784 nm), Co (λ=228.616 nm) and Ni (λ=221.647nm). Analysis of doped or undoped alkali-deficient nickel oxide samplesfor metals can be performed by a commercial analytical laboratory, forexample, Galbraith Laboratories, Inc. (Knoxville, Tenn.). Proton contentcan be analyzed using a type of neutron activation analysis known as“PGAA (Prompt Gamma-ray Activation Analysis) at University ofTexas-Austin using the general methods described, for example, by G. L.Molnar (Handbook of Prompt Gamma Activation Analysis, Dordrecht, TheNetherlands: Kluwer Academic Publishers, 2004). The average oxidationstate of the nickel and the transition metal dopants (e.g., Mn, Co) inthe lithium deficient metal-doped nickel oxide can be determined bychemical titrimetry using ferrous ammonium sulfate and standardizedpotassium permanganate solutions as described, for example, by A. F.Dagget and W. B. Meldrun (Quantitative Analysis, Boston: Heath, 1955,408-9). The average oxidation state of the transition metals also can bedetermined indirectly from the specific gravimetric capacity observedfor coin cells including the lithium deficient metal-doped nickel oxideas the cathode active material, Li metal as the anode active material,and a non-aqueous electrolyte solution.

Elemental analyses of selected compositions of doped and undoped alkalinickel oxide powders can be performed. Samples can be measured usinginductively coupled plasma atomic emission spectroscopy (“ICP-AE”) by acommercial analytical laboratory (e.g., Galbraith Laboratories, Inc.,Knoxville, Tenn.).

True densities of an alkali-deficient nickel oxide and the correspondingprecursor nickel oxide can be measured by a He gas pycnometer (e.g.,Quantachrome Ultrapyc Model 1200e) as described in general by P. A. Webb(“Volume and Density Determinations for Particle Technologists”,Internal Report, Micromeritics Instrument Corp., 2001, pp. 8-9) and in,for example, ASTM Standard D5965-02 (“Standard Test Methods for SpecificGravity of Coating Powders”, ASTM International, West Conshohocken, Pa.,2007) and ASTM Standard B923-02 (“Standard Test Method for Metal PowderSkeletal Density by Helium or Nitrogen Pycnometry”, ASTM International,West Conshohocken, Pa., 2008). True density is defined, for example, bythe British Standards Institute, as the mass of a particle divided byits volume, excluding open and closed pores.

Inclusion of a stabilized delithiated nickel oxide containingtetravalent nickel (i.e., Ni(IV)) in a cathode active material cansubstantially improve overall discharge performance of primary alkalinebatteries compared to batteries including conventional cathode activematerials (e.g., electrolytic manganese dioxide (EMD) or β-nickeloxyhydroxide). In some embodiments, alkaline batteries with cathodesincluding Ni(IV)-containing active materials can exhibit an initial or“fresh” (i.e., measured within about one hour of cell closure) opencircuit voltage (OCV) of greater than about 1.90 V and less than about2.10 V. Without wishing to be bound by theory, it is believed thatalkaline batteries with cathodes including nickel (IV)-containing activematerials having a lower OCV (e.g., less than about 1.75 V, less thanabout 1.70 V) can be advantageous for use with certain battery-poweredelectronic devices, such as devices designed for use with standardcommercial alkaline batteries. In some embodiments, alkaline batterieswith cathodes including nickel (IV)-containing active materials can haveadequate capacity retention after storage for longer than about 1-2weeks at ambient room temperature (e.g., or at elevated temperaturessuch as 45° C. or 60° C.) for extended periods of time (e.g., for oneweek or longer, two weeks or longer, three weeks or longer), which canprovide batteries with a useful shelf life.

In some embodiments, alkaline batteries with cathodes including alkalideficient metal-doped nickel (IV) oxide can have decreased internal gaspressure buildup during storage. Without wishing to be bound by theory,it is believed that the gradual buildup of gas pressure during storagecan result from generation of oxygen gas due to degradation of thealkaline electrolyte, via oxidation of water by nickel (IV) at high OCV,as shown in Equation 1.

Li_(x)Ni(IV)_(1-x)Ni(III)_(x)O₂+H₂O→Ni(II)(OH)₂ +xLi⁺+½O₂  (1)

In some embodiments, the metal doped alkali-deficient nickel oxidepowder has a cumulative oxygen evolution volume after storing for threeweeks at 25° C. in alkaline electrolyte solution of less than 5 cm³/g(e.g., less than 6 cm³/g, less than 7 cm³/g,). In some embodiments, thecorresponding value for undoped alkali-deficient nickel oxide powder isgreater than 8.5 cm³/g.

An increase in the internal gas pressure of a cell can be undesirable,as product safety can be compromised for the consumer. For example, anincrease in internal pressure can cause the battery to leak and/or ventif the gas pressure becomes sufficiently high. In some embodiments,decreasing the initial OCV of alkaline primary batteries having cathodesincluding alkali deficient metal-doped nickel (IV) oxide activematerials can decrease the overall rate of oxygen generation, resultingin less gas pressure buildup during long term storage.

In some embodiments, the alkali-deficient metal-doped nickel oxide has anominal low rate capacity of at least 350 mAh/g (e.g., at least 375mAh/g) and a high rate capacity of at least 360 mAh/g when dischargedafter storing for 24 hours at 25° C. The alkali-deficient metal-dopednickel oxide can have a low rate capacity of at least 340 mAh/g (e.g.,at least 350 mAh/g, at least 360 mAh/g) after storing for one week at25° C. The alkali-deficient metal-doped nickel oxide can have a nominallow rate capacity of at least 300 mAh/g (e.g., at least 310 mAh/g, atleast 320 mAh/g, at least 330 mAh/g, at least 340 mAh/g after storingfor one week at 45° C.

In some embodiments, alkaline cells with cathodes including thealkali-deficient metal-doped nickel oxide have a capacity retention ofat least 90 percent (e.g., at least 95%) when discharged at a nominallylow rate after storing for one week at 25° C. Alkaline cells withcathodes including the metal doped alkali-deficient nickel oxide canhave a capacity retention of at least 80 percent (e.g., at least 85percent) when discharged at a nominally low rate after storing for oneweek at 45° C.

In general, an alkali-deficient nickel oxide can be prepared bytreatment of a layered lithium nickel oxide precursor having a nominalstoichiometric formula of LiNiO₂ with a 2-12 M aqueous solution of astrong mineral acid (e.g., sulfuric acid, nitric acid, hydrochloricacid) at a temperature below ambient room temperature (e.g., betweenabout 0 and 5° C.) for various periods of time ranging between 20 and 60hours. Nearly all the lithium ions can be extracted from the interlayerregions between the Ni-oxygen layers in the crystal lattice. A suitablelayered lithium nickel oxide precursor having specific physicochemicalproperties can be synthesized from a commercial spherical nickelhydroxide by any of several methods including both high and lowtemperature processes. For example, a layered lithium nickel oxideprecursor can be synthesized by procedures described by Ohzuku andco-workers (J. Electrochem. Soc., 1993, 140, 1862); Ebner and co-workers(Solid State Ionics, 1994, 69, 238); U.S. Pat. Nos. 4,980,080;5,180,574; 5,629,110; and 5,264,201, each herein incorporated byreference in its entirety. A layered lithium nickel oxide precursorhaving at least a portion of the nickel ions substituted by one or moreother metal ions or non-metal ions can be prepared, for example, via asolid state reaction of a mixture of suitable metal-containing precursorpowders, as described, for example, in U.S. Pat. No. 4,980,080, U.S.Pat. No. 5,629,110, U.S. Pat. No. 5,955,051, U.S. Pat. No. 5,720,932,U.S. Pat. No. 6,274,270, and U.S. Pat. No. 6,335,119, each hereinincorporated by reference in its entirety. The metal ions can be atransition metal ions (e.g., Co, Mn, Y), alkaline earth metal ions(e.g., Ca, Mg) or main group metal ions (e.g., Al, Sn). Non-metal ions(e.g., B, Si, Ge) can be substituted for Ni ions and/or Li ions.

In some embodiments, to prepare an undoped lithium nickel oxide, anundoped nickel oxide can be mixed with a stoichiometric amount (i.e.,1:1) of lithium hydroxide monohydrate (LiOH.H₂O) using a high-energymilling process (e.g., a high-energy shaker mill, a planetary mill, astirred ball mill, a small media mill). The mixture can be heatedsequentially at two different heat treatment temperatures in flowingoxygen gas. For example, initially, the mixture can be heated to about210° C. (about 0.5° C./min), held for at temperature for 16-20 hours,and then allowed to furnace cool (in an oxygen flow) to ambient roomtemperature. Next, the mixture can be re-milled, heated to about 800° C.(0.5° C./min) with, for example, two intermediate temperature soaks(i.e., at about 150° C. for 30 minutes; at about 350° C. for 3 hours),held at about 800° C. for 48 hours, and finally allowed to furnace coolto ambient room temperature.

In some embodiments, to prepare a multiple metal-doped lithium nickeloxide, an undoped β-nickel oxyhydroxide powder and selected metal ionsources, for example, aluminum metal powder, aluminum hydroxide (e.g.,Al(OH)₃), cobalt oxide (e.g., Co₃O₄), cobalt carbonate (CoCO₃),magnesium oxide (MgO), calcium oxide (CaO), calcium hydroxide (Ca(OH)₂),calcium carbonate (CaCO₃), yttrium oxide (Y₂O₃), yttrium hydroxide(Y(OH)₃), manganese oxide (MnO, Mn₂O₃, MnO₂), manganese carbonate(MnCO₃), and/or lithium hydroxide monohydrate in specifiedstoichiometric ratios can be mixed by a high-energy milling process.Stoichiometries of the compositions can be selected according tocomposition diagrams corresponding to selected ternary lithiummetal-doped nickel oxide systems, for example,LiNi_(1-y-z)Co_(y)Mg_(z)O₂ and LiNi_(1-y-z)Co_(y)Al_(z)O₂. Thehigh-energy milled mixtures including nickel oxyhydroxide and variousmetal ion sources serving as precursors to the metal-doped lithiumnickel oxides can be heated as above for the undoped lithium nickeloxide.

In some embodiments, at least a portion of the Ni ions in a layeredlithium nickel oxide precursor can be substituted by one or morenon-metal ions (e.g., B, Si, Ge). A mixed metal and nonmetal-dopedlithium nickel oxide can be prepared by blending an undoped β-nickeloxyhydroxide powder, selected metal sources, and selected nonmetalsources, for example, boron oxide (B₂O₃), silicon powder (Si), silicondioxide (SiO₂), germanium powder (Ge), germanium dioxide (GeO₂) and/orlithium hydroxide monohydrate in specified stoichiometric ratios andthoroughly mixing by a high-energy milling process. The high-energymilled mixtures including the nickel oxyhydroxide and the variousnonmetal and metal sources serving as precursors to the mixed nonmetaland metal-doped lithium nickel oxides can be heated as above for themetal-doped lithium nickel oxides.

In some embodiments, the doped alkali nickel oxides can be prepared viaa modified solid-state process. For example, the nickel source materialcan be a commercial spherical β-nickel oxyhydroxide powder that iseither undoped, or where the nickel is partially substituted by about2-3 atomic % cobalt. The β-nickel oxyhydroxide can be prepared bychemical oxidation of β-nickel hydroxide as follows. An excess of solidsodium peroxydisulfate Na₂S₂O₈ can be added in portions to a stirredslurry of a commercial spherical cobalt-substituted (or unsubstituted)β-nickel hydroxide powder in de-ionized water at about 30-40° C. Themixture can then be heated to about 50-60° C. and stirred for about 15hours with incremental addition of portions of aqueous NaOH solution orsolid powder to maintain pH in the range of 8<pH<12 (e.g., at about 10).Next, the stirring and heating can be stopped and the resultingsuspension of black particles can be allowed to settle (e.g., for 1-4hours). A clear supernatant liquid can be removed and the particles canbe re-suspended in a fresh aliquot of water (e.g., de-ionized water).This suspension can be stirred for 5-30 minutes, allowed to settle, thesupernatant removed, and the entire process can be repeated until the pHof the supernatant is nearly neutral (e.g., 6<pH<8, or about 7). Thewashed β-nickel oxyhydroxide product can be dried in air at about80-100° C.

In some embodiments, preparation of nickel(IV)-containing cathode activematerials requires removal of most of the interlayer Li ions from thelayered lithium nickel oxide precursors. In some embodiments, the Liions are chemically extracted via an oxidative delithiation process.Oxidative delithiation of a layered lithium nickel oxide can take placevia a proton catalyzed aqueous disproportionation process such as thatdescribed in Equation 2 and as reported by H. Arai and coworkers (J.Solid State Chem., 2002, 163, 340-9). For example, treatment of alayered lithium nickel oxide powder with an aqueous 6M H₂SO₄ solution atvery low pH can cause Ni(III) ions on the surfaces of the particles todisproportionate into equal numbers of Ni(II) and Ni(IV) ions.

2LiNi⁺³O₂+4H⁺→Ni⁺⁴O₂+Ni⁺²+2Li⁺+2H₂O  (2)

The Ni(II) ions can dissolve in the acid solution whereas the Ni(IV)ions are insoluble and can remain in the solid phase.

In some embodiments, ionic exchange of Li ions by protons can take placevia hydrolysis such as described in Equation 3. However, theintroduction of protons into lattice sites formerly occupied by Li ionsin the interlayer region can be undesirable since these protons canremain in the lattice even after acid treatment, and inhibit thedisproportionation reaction. Further, these protons can interfere withsolid state diffusion of protons inserted during discharge of cellsincluding the lithium deficient nickel oxide as active cathode materialas well as limit total discharge capacity.

LiNi⁺³O₂+H₂O→H_(x)Li_((1-x))Ni⁺³O₂ +xLiOH  (3)

An improved process for oxidative delithiation of metal-substitutedlayered lithium nickel oxides by treatment with an aqueous solution of amineral acid at a relatively low temperature (e.g., between 0° C. and 5°C.) was described, for example, in U.S. application Ser. No. 12/722,669.After treatment by the low-temperature acid washing process in U.S.application Ser. No. 12/722,669, the isolated solid product can exhibita total weight loss of about 50% relative to the initial dry weight ofthe corresponding metal-substituted LiNi_(1-y-z)Co_(y)M_(z)O₂ phase.This weight loss can be attributed to, for example, the partialdissolution of Ni(II) ions as well as the extraction of Li⁺ions.Dissolution of Ni⁺² ions from the surface of the lithium nickel oxideparticles can increase particle porosity thereby increasing exposure ofNi⁺³ ions inside the particles to acid and resulting additionaldisproportionation. An increase in the amount of disproportionation canserve to raise the average Ni oxidation state. In some embodiments, thealkali-deficient nickel oxide is prepared as described, for example, inU.S. application Ser. No. 12/722,669, herein incorporated by referencein its entirety.

In some embodiments, the alkali-deficient nickel oxide includes protons.For example, the alkali-deficient nickel oxide can include protons at astoichiometric ratio of between 0.01 and 0.2 atomic percent.

X-ray powder diffraction patterns of selected compositions ofdelithiated metal substituted nickel oxide powders can be measured inthe same manner as the corresponding metal substituted lithium nickeloxides. The observed patterns can be consistent with those reportedpreviously, for example, by H. Arai et al. (e.g., J. Solid State Chem.,2002, 163, 340-9) and also L. Croguennec et al. (e.g., J. Mater. Chem.,2001, 11, 131-41) for other chemically delithiated layered nickel oxideshaving various compositions. The experimental patterns can be consistentwith that reported by T. Ohzuku et al. (e.g., J. Electrochem. Soc.,1993, 140, 1862) for a comparable sample of delithiated nickel oxide.

The alkali-deficient nickel oxide resulting from repeated acid treatmentcan have greater purity, greater B.E.T. specific surface area, and/orlarger average pore diameter relative to the alkali metal-containingprecursor nickel oxide. The specific surface areas of analkali-deficient nickel oxide and the corresponding precursor nickeloxide can be determined by the multipoint B.E.T. N₂ adsorption isothermmethod described, for example, by P. W. Atkins (Physical Chemistry,5^(th) edn., New York: W. H. Freeman & Co., 1994, pp. 990-992) and S.Lowell et al. (Characterization of Porous Solids and Powders: PowderSurface Area and Porosity, Dordrecht, The Netherlands: Springer, 2006,pp. 58-80). The B.E.T. surface area method measures the total surfacearea on the exterior surfaces of particles and includes that portion ofthe surface area defined by open pores within the particle accessiblefor gas adsorption and desorption. In some embodiments, the specificsurface area of the alkali-deficient nickel oxide can be substantiallygreater than that of the precursor nickel oxide. An increase in specificsurface area can be correlated with an increase in surface roughness andporosity, which also can be assessed by analyzing the microstructure ofthe nickel oxide particles as imaged by scanning electron microscopy(e.g., SEM micrographs at about 10,000× magnification). Porosimetricmeasurements can be performed on the nickel oxide powders to determinecumulative pore volumes, average pore sizes (i.e., diameters), and poresize distributions. Pore sizes and pore size distributions can becalculated by applying various models and computational methods (e.g.,BJH, DH, DR, HK, SF, etc.) to analyze the data from the measurement ofN₂ adsorption and/or desorption isotherms, as discussed, for example, byS. Lowell et al. (Characterization of Porous Solids and Powders: PowderSurface Area and Porosity, Dordrecht, The Netherlands: Springer, 2006,pp. 101-156).

In some embodiments, cathode 12 can include between 50 percent and 95percent by weight (e.g., between 60 percent and 90 percent by weight,between 70 percent and 85 percent by weight) of the cathode activematerial. Cathode 12 can include greater than or equal to 50, 60, 70,80, or 90 percent by weight, and/or less than or equal to 95, 90, 80,70, or 60 percent by weight of the cathode active material. Cathode 12can include one or more (e.g., two, three or more) doped and/or undopedalkali-deficient nickel oxides, in any combination. For example, cathode12 can include a mixture of Li_(x)Ni_(1-y)Co_(y)O₂,Li_(x)Ni_(1-y-z)Co_(y)M^(a) _(z)O₂, Li_(x)Ni_(1-y-z-w)Co_(y)M^(a)_(z)M^(b) _(w)O₂, and/or Li_(x)NiO₂, where M^(a) is Ca, Mg, Al, Y,and/or Mn.

One or more alkali-deficient nickel oxides can make up all of the activematerial of cathode 12, or a portion of the active material of cathode12. In a cathode including a mixture or blend of active materials, theactive materials can include greater than about one percent to less thanabout 100 percent by weight of the alkali-deficient nickel oxide. Forexample, cathode 12 can include greater than 0%, 1%, 5%, 10%, 20%, 50%,or 70% by weight of the alkali-deficient nickel oxide (s); and/or lessthan or equal to about 100%, 70%, 50%, 20%, 10%, 5%, or 1% by weight ofthe alkali-deficient nickel oxide(s). Other examples of suitable cathodeactive materials that can be used in combination with thealkali-deficient nickel oxide(s) can be selected from γ-MnO₂ (e.g., EMD,CMD), β-NiOOH, γ-NiOOH, AgO, Ag₂O, AgNiO₂, AgCoO₂, AgCo_(x)Ni_(1-x)O₂,AgCuO₂, Ag₂Cu₂O₃, and combinations thereof.

In some embodiments, cathode 12 can include an electrically conductiveadditive capable of enhancing the bulk electrical conductivity ofcathode 12. Examples of conductive additives include graphite, carbonblack, silver powder, gold powder, nickel powder, carbon fibers, carbonnanofibers, carbon nanotubes, acetylene black, manganese dioxide, cobaltoxide, cobalt oxyhydroxide, silver oxide, silver nickel oxide, nickeloxyhydroxide, and indium oxide. Preferred conductive additives includegraphite particles, graphitized carbon black particles, carbonnanofibers, vapor phase grown carbon fibers, and single and multiwallcarbon nanotubes. In certain embodiments, the graphite particles can benon-synthetic (i.e., “natural”), nonexpanded graphite particles, forexample, NdG MP-0702X available from Nacional de Grafite (Itapecirica,Brazil) and Formula BT™ grade available from Superior Graphite Co.(Chicago, Ill.). In other embodiments, the graphite particles can beexpanded natural or synthetic graphite particles, for example, Timrex®BNB90 available from Timcal, Ltd. (Bodio, Switzerland), WH20 or WH20Agrade from Chuetsu Graphite Works Co., Ltd. (Osaka, Japan), and ABGgrade available from Superior Graphite Co. (Chicago, Ill.). In yet otherembodiments, the graphite particles can be synthetic, non-expandedgraphite particles, for example, Timrex® KS4, KS6, KS15, MX15 availablefrom Timcal, Ltd. (Bodio, Switzerland). The graphite particles can beoxidation-resistant synthetic, non-expanded graphite particles. The term“oxidation resistant graphite” as used herein refers to a syntheticgraphite made from high purity carbon or carbonaceous materials having ahighly crystalline structure. Suitable oxidation resistant graphitesinclude, for example, SFG4, SFG6, SFG10, SFG15 available from Timcal,Ltd., (Bodio, Switzerland). The use of oxidation resistant graphite inblends with another strongly oxidizing cathode active material, nickeloxyhydroxide, is disclosed in commonly assigned U.S. Ser. No.11/820,781, filed Jun. 20, 2007. Carbon nanofibers are described, forexample, in commonly-assigned U.S. Pat. No. 6,858,349 and U.S. PatentApplication Publication No. US 2002-0172867A1. Cathode 12 can includebetween 3% and 35%, between 4% and 20%, between 5% and 10%, or between6% and 8% by weight of conductive additive.

An optional binder can be added to cathode 12 to enhance structuralintegrity. Examples of binders include polymers such as polyethylenepowders, polypropylene powders, polyacrylamides, and variousfluorocarbon resins, for example polyvinylidene difluoride (PVDF) andpolytetrafluoroethylene (PTFE). An example of a suitable polyethylenebinder is available from Dupont Polymer Powders (Sari, Switzerland)under the tradename Coathylene HX1681. The cathode 12 can include, forexample, from 0.05% to 5% or from 0.1% to 2% by weight binder relativeto the total weight of the cathode. Cathode 12 can also include otheroptional additives.

The electrolyte solution also is dispersed throughout cathode 12, e.g.,at about 5-7 percent by weight. Weight percentages provided above andbelow are determined after the electrolyte solution was dispersed incathode 12. The electrolyte solution can be any of the electrolytesolutions commonly used in alkaline batteries. The electrolyte solutioncan be an alkaline solution, such as an aqueous alkali metal hydroxidesolution, e.g., LiOH, NaOH, KOH, or mixtures of alkali metal hydroxidesolutions (e.g., KOH and NaOH, KOH and LiOH). For example, the aqueousalkali metal hydroxide solution can include between about 33 and about45 percent by weight of the alkali metal hydroxide, such as about 9 NKOH (i.e., about 37% by weight KOH). In some embodiments, theelectrolyte solution also can include up to about 6 percent by weightzinc oxide, e.g., about 2 percent by weight zinc oxide.

Anode 14 can be formed of any of the zinc-based materials conventionallyused in alkaline battery zinc anodes. For example, anode 14 can be agelled zinc anode that includes zinc metal particles and/or zinc alloyparticles, a gelling agent, and minor amounts of additives, such as agassing inhibitor. A portion of the electrolyte solution can bedispersed throughout the anode. The zinc particles can be any of thezinc-based particles conventionally used in gelled zinc anodes. Thezinc-based particles can be formed of a zinc-based material, forexample, zinc or a zinc alloy. Generally, a zinc-based particle formedof a zinc-alloy is greater than 75% zinc by weight, generally greaterthan 99.9% by weight zinc. The zinc alloy can include zinc (Zn) and atleast one of the following elements: indium (In), bismuth (Bi), aluminum(Al), calcium (Ca), gallium (Ga), lithium (Li), magnesium (Mg), and tin(Sn). The zinc alloy generally is composed primarily of zinc andpreferably can include metals that can inhibit gassing, such as indium,bismuth, aluminum and mixtures thereof. As used herein, gassing refersto the evolution of hydrogen gas resulting from a reaction of zinc metalor zinc alloy with the electrolyte. The presence of hydrogen gas insidea sealed battery is undesirable because a pressure buildup can causeleakage of electrolyte. Preferred zinc-based particles are bothessentially mercury-free and lead-free. Examples of zinc-based particlesinclude those described in U.S. Pat. Nos. 6,284,410; 6,472,103;6,521,378; and commonly-assigned U.S. application Ser. No. 11/001,693,filed Dec. 1, 2004, all hereby incorporated by reference. The terms“zinc”, “zinc powder”, or “zinc-based particle” as used herein shall beunderstood to include zinc alloy powder having a high relativeconcentration of zinc and as such functions electrochemicallyessentially as pure zinc. The anode can include, for example, betweenabout 60% and about 80%, between about 62% and 75%, between about 63%and about 72%, or between about 67% and about 71% by weight ofzinc-based particles. For example, the anode can include less than about72%, about 70%, about 68%, about 64%, or about 60%, by weight zinc-basedparticles.

The zinc-based particles can be formed by various spun or air blownprocesses. The zinc-based particles can be spherical or non-spherical inshape. Non-spherical particles can be acicular in shape (i.e., having alength along a major axis at least two times a length along a minoraxis) or flake-like in shape (i.e., having a thickness not more than 20%of the length of the maximum linear dimension). The surfaces of thezinc-based particles can be smooth or rough. As used herein, a“zinc-based particle” refers to a single or primary particle of azinc-based material rather than an agglomeration or aggregation of morethan one particle. A percentage of the zinc-based particles can be zincfines. As used herein, zinc fines include zinc-based particles smallenough to pass through a sieve of 200 mesh size (i.e., a sieve having aTyler standard mesh size corresponding to a U.S. Standard sieve havingsquare openings of 0.075 mm on a side) during a normal sieving operation(i.e., with the sieve shaken manually). Zinc fines capable of passingthrough a 200 mesh sieve can have a mean average particle size fromabout 1 to 75 microns, for example, about 75 microns. The percentage ofzinc fines (i.e., −200 mesh) can make up about 10 percent, 25 percent,50 percent, 75 percent, 80 percent, 90 percent, 95 percent, 99 percentor 100 percent by weight of the total zinc-based particles. A percentageof the zinc-based particles can be zinc dust small enough to passthrough a 325 mesh size sieve (i.e., a sieve having a Tyler standardmesh size corresponding to a U.S. Standard sieve having square openingsof 0.045 mm on a side) during a normal sieving operation. Zinc dustcapable of passing through a 325 mesh sieve can have a mean averageparticle size from about 1 to 35 microns (for example, about 35microns). The percentage of zinc dust can make up about 10 percent, 25percent, 50 percent, 75 percent, 80 percent, 90 percent, 95 percent, 99percent or 100 percent by weight of the total zinc-based particles. Evenvery small amounts of zinc fines, for example, at least about 5 weightpercent, or at least about 1 weight percent of the total zinc-basedparticles can have a beneficial effect on anode performance. The totalzinc-based particles in the anode can consist of only zinc fines, of nozinc fines, or mixtures of zinc fines and dust (e.g., from about 35 toabout 75 weight percent) along with larger size (e.g., −20 to +200 mesh)zinc-based particles. A mixture of zinc-based particles can provide goodoverall performance with respect to rate capability of the anode for abroad spectrum of discharge rate requirements as well as provide goodstorage characteristics. To improve performance at high discharge ratesafter storage, a substantial percentage of zinc fines and/or zinc dustcan be included in the anode.

Anode 14 can include gelling agents, for example, a high molecularweight polymer that can provide a network to suspend the zinc particlesin the electrolyte. Examples of gelling agents include polyacrylicacids, grafted starch materials, salts of polyacrylic acids,polyacrylates, carboxymethylcellulose, a salt of acarboxymethylcellulose (e.g., sodium carboxymethylcellulose) orcombinations thereof. Examples of polyacrylic acids include Carbopol 940and 934 available from B.F. Goodrich Corp. and Polygel 4P available from3V. An example of a grafted starch material is Waterlock A221 or A220available from Grain Processing Corp. (Muscatine, Iowa). An example of asalt of a polyacrylic acid is Alcosorb G1 available from CibaSpecialties. The anode can include, for example, between about 0.05% and2% by weight or between about 0.1% and 1% by weight of the gelling agentby weight.

Gassing inhibitors can include a metal, such as bismuth, tin, indium,aluminum or a mixture or alloys thereof. A gassing inhibitor also caninclude an inorganic compound, such as a metal salt, for example, anindium or bismuth salt (e.g., indium sulfate, indium chloride, bismuthnitrate). Alternatively, gassing inhibitors can be organic compounds,such as phosphate esters, ionic surfactants or nonionic surfactants.Examples of ionic surfactants are disclosed in, for example, U.S. Pat.No. 4,777,100, which is hereby incorporated by reference.

Separator 16 can have any of the conventional designs for primaryalkaline battery separators. In some embodiments, separator 16 can beformed of two layers of a non-woven, non-membrane material with onelayer being disposed along a surface of the other. To minimize thevolume of separator 16 while providing an efficient battery, each layerof non-woven, non-membrane material can have a basic weight of about 54grams per square meter, a thickness of about 5.4 mils when dry and athickness of about 10 mils when wet. In these embodiments, the separatorpreferably does not include a layer of membrane material or a layer ofadhesive between the non-woven, non-membrane layers. Generally, thelayers can be substantially devoid of fillers, such as inorganicparticles. In some embodiments, the separator can include inorganicparticles. In other embodiments, separator 16 can include a layer ofcellophane combined with a layer of non-woven material. The separatoroptionally can include an additional layer of non-woven material. Thecellophane layer can be adjacent to cathode 12. Preferably, thenon-woven material can contain from about 78% to 82% by weightpolyvinylalcohol (PVA) and from about 18% to 22% by weight rayon and atrace amount of surfactant. Such non-woven materials are available fromPDM under the tradename PA25. An example of a separator including alayer of cellophane laminated to one or more layers of a non-wovenmaterial is Duralam DT225 available from Duracell Inc. (Aarschot,Belgium).

In yet other embodiments, separator 16 can be an ion-selectiveseparator. An ion-selective separator can include a microporous membranewith an ion-selective polymeric coating. In some cases, such as inrechargeable alkaline manganese dioxide cells, diffusion of solublezincate ion, i.e., [Zn(OH)₄]²⁻, from the anode to the cathode caninterfere with the reduction and oxidation of manganese dioxide, therebyresulting in a loss of coulombic efficiency and ultimately in decreasedcycle life. Separators that can selectively inhibit the passage ofzincate ions, while allowing free passage of hydroxide ions aredescribed in U.S. Pat. Nos. 5,798,180 and 5,910,366. An example of aseparator includes a polymeric substrate having a wettable celluloseacetate-coated polypropylene microporous membrane (e.g., Celgard® 3559,Celgard® 5550, Celgard® 2500, and the like) and an ion-selective coatingapplied to at least one surface of the substrate. Suitable ion-selectivecoatings include polyaromatic ethers (such as a sulfonated derivative ofpoly(2,6-dimethyl-1,4-phenyleneoxide)) having a finite number ofrecurring monomeric phenylene units each of which can be substitutedwith one or more lower alkyl or phenyl groups and a sulfonic acid orcarboxylic acid group. In addition to preventing migration of zincateions to the manganese dioxide cathode, the selective separator wasdescribed in U.S. Pat. Nos. 5,798,180 and 5,910,366 as capable ofdiminishing diffusion of soluble ionic species away from the cathodeduring discharge

Alternatively or in addition, the separator can prevent substantialdiffusion of soluble ionic metal species (e.g., Ag⁺, Ag²⁺, Cu⁺, Cu²⁺,Bi⁵⁺, and/or Bi³⁺) away from the cathode to the zinc anode, such as theseparator described in U.S. Pat. No. 5,952,124. The separator caninclude a substrate membrane such as cellophane, nylon (e.g., Pellon®sold by Freundenburg, Inc.), microporous polypropylene (e.g., Celgard®3559 sold by Celgard, Inc.) or a composite material including adispersion of a carboxylic ion-exchange material in a microporousacrylic copolymer (e.g., PD2193 sold by Pall-RAI, Inc.). The separatorcan further include a polymeric coating thereon including a sulfonatedpolyaromatic ether, as described in U.S. Pat. Nos. 5,798,180; 5,910,366;and 5,952,124.

In other embodiments, separator 16 can include an adsorptive or trappinglayer. Such a layer can include inorganic particles that can form aninsoluble compound or an insoluble complex with soluble transition metalspecies to limit diffusion of the soluble transition metal speciesthrough the separator to the anode. The inorganic particles can includemetal oxide nanoparticles, for example, as ZrO₂ and TiO₂. Although suchan adsorptive separator can attenuate the concentration of the solubletransition metal species, it may become saturated and lose effectivenesswhen high concentrations of soluble metal species are adsorbed. Anexample of such an adsorptive separator is disclosed in commonlyassigned U.S. Pat. Nos. 7,914,920 and 8,048,556.

Battery housing 18 can be any conventional housing commonly used forprimary alkaline batteries. The battery housing 18 can be fabricatedfrom metal, for example, nickel-plated cold-rolled steel. The housinggenerally includes an inner electrically-conductive metal wall and anouter electrically non-conductive material such as heat shrinkableplastic. An additional layer of conductive material can be disposedbetween the inner wall of the battery housing 18 and cathode 12. Thislayer may be disposed along the inner surface of the wall, along thecircumference of cathode 12 or both. This conductive layer can beapplied to the inner wall of the battery, for example, as a paint ordispersion including a carbonaceous material, a polymeric binder, andone or more solvents. The carbonaceous material can be carbon particles,for example, carbon black, partially graphitized carbon black orgraphite particles. Such materials include LB1000 (Timcal, Ltd.),Eccocoat 257 (W. R. Grace & Co.), Electrodag 109 (Acheson Colloids,Co.), Electrodag 112 (Acheson), and EB0005 (Acheson). Methods ofapplying the conductive layer are disclosed in, for example, CanadianPatent No. 1,263,697, which is hereby incorporated by reference.

The anode current collector 20 passes through seal 22 extending intoanode 14. Current collector 20 is made from a suitable metal, such asbrass or brass-plated steel. The upper end of current collector 20electrically contacts the negative top cap 24. Seal 22 can be made, forexample, of nylon.

Battery 10 can be assembled using conventional methods and hermeticallysealed by a mechanical crimping process. In some embodiments, positiveelectrode 12 can be formed by a pack and drill method, described in U.S.Ser. No. 09/645,632, filed Aug. 24, 2000.

Battery 10 can be a primary electrochemical cell or in some embodiments,a secondary electrochemical cell. Primary batteries are meant to bedischarged (e.g., to exhaustion) only once, and then discarded. In otherwords, primary batteries are not intended to be recharged. Primarybatteries are described, for example, by D. Linden and T. B. Reddy(Handbook of Batteries, 3^(rd) ed., New York: McGraw-Hill Co., Inc.,2002). In contrast, secondary batteries can be recharged many times(e.g., more than fifty times, more than a hundred times, more than athousand times). In some cases, secondary batteries can includerelatively robust separators, such as those having many layers and/orthat are relatively thick. Secondary batteries can also be designed toaccommodate changes, such as swelling, that can occur in the batteries.Secondary batteries are described, for example, by T. R. Crompton(Battery Reference Book, 3^(rd) ed., Oxford: Reed Educational andProfessional Publishing, Ltd., 2000) and D. Linden and T. B. Reddy(Handbook of Batteries, 3^(rd) ed., New York: McGraw-Hill Co., Inc.,2002).

Battery 10 can have any of a number of different nominal dischargevoltages (e.g., 1.2 V, 1.5 V, 1.65 V), and/or can be, for example, a AA,AAA, AAAA, C, or D battery. While battery 10 can be cylindrical, in someembodiments, battery 10 can be non-cylindrical. For example, battery 10can be a coin cell, a button cell, a wafer cell, or a racetrack-shapedcell. In some embodiments, a battery can be prismatic. In certainembodiments, a battery can have a rigid laminar cell configuration or aflexible pouch, envelope or bag cell configuration. In some embodiments,a battery can have a spirally wound configuration, or a flat plateconfiguration. Batteries are described, for example, in U.S. Pat. No.6,783,893; U.S. Patent Application Publication No. 2007/0248879 Al,filed on Jun. 20, 2007; and U.S. Pat. No. 7,435,395.

The following examples are illustrative and not intended to be limiting.

EXAMPLES Example 1 Synthesis of LiNiO₂

A stoichiometric lithium nickel oxide, LiNiO₂ was synthesized byblending 93.91 g of a commercial spherical β-nickel oxyhydroxide powder(e.g., β-NiOOH, Kansai Catalyst Co.) and 42.97 g of a monohydratedlithium hydroxide (LiOH.H₂O, Aldrich Chemical) and heating the mixtureat about 210° C. in a tube furnace for about 20 hours under an oxygengas flow. The heated mixture was allowed to furnace cool to ambient roomtemperature, ground with a mortar and pestle, and re-heated at 800° C.for an additional 48 hours under flowing oxygen gas. The x-ray powderdiffraction pattern of the final reaction product corresponded closelyto that reported for stoichiometric LiNiO₂ (e.g., ICDD PDF No. 09-0063),as described, for example, in U.S. Pat. No. 5,720,932, J. Maruta et al.(Journal of Power Sources, 2000, 90, 89-94) and Y. Sun et al. (SolidState Ionics, 2006, 177, 1173-7).

Example 2 Synthesis of Delithiated Li_(x)NiO₂

The lithium nickelate of Example 1 was delithiated by a low-temperatureacid treatment process similar to that disclosed in Example 1 of U.S.application Ser. No. 12/722,669, herein incorporated in its entirety.Specifically, approximately 100 g of LiNiO₂ was added to 1.5 L of arapidly stirred aqueous 6 M H₂SO₄ solution cooled to between 0 and 5° C.The resulting slurry is stirred and maintained at about 2° C. for eitherabout 20 hours (Ex. 2a) or 40 hours (Ex. 2b). Next, the suspended solidswere allowed to settle, the supernatant liquid removed by decantation,and the solid washed with aliquots of de-ionized water until the pH ofthe supernatant was nearly neutral (i.e., pH ˜6-7). The solid wascollected by either pressure or vacuum filtration and dried at about 80°C. in air for about 24 hours. The residual lithium content of the dried,delithiated Li_(x)NiO₂ product was determined by ICP spectroscopy to beless than 2.2 wt % Li, corresponding to x=0.31 (Ex. 2a) and greater than0.4 wt % Li, corresponding to x=0.06 (Ex. 2b). The x-ray powderdiffraction pattern of the delithiated product was similar to that ofthe stoichiometric LiNiO₂ with the expected shifts in the positions ofthe diffraction peaks to higher 2θ angles. Average particle size of thedelithiated Li_(x)NiO₂ powder ranged from about 1 to 8 μm and the B.E.T.specific surface area was about 1.36 m²/g. The true density of theLi_(x)NiO₂ powder was measured by He pycnometer as 4.70 g/cm³.

The electrochemical discharge performance of the delithiated Li_(x)NiO₂was evaluated in 635-type alkaline button cells. Generally, button cellswere assembled in the following manner. Dried Li_(x)NiO₂ powder wasblended together manually with an oxidation resistant graphite (e.g.,Timrex SFG-15 from Timcal) and a KOH electrolyte solution containing35.3 wt % KOH and 2 wt % zinc oxide in a weight ratio of 75:20:5 using amortar and pestle to form a wet cathode mix. About 0.45 g of the wetcathode mix was pressed into a nickel grid welded to the bottom of thecathode can of the cell. A disk of porous separator material including alayer of cellophane bonded to a non-woven polymeric layer (e.g.,“Duralam” or PDM “PA25”) and saturated with electrolyte solution waspositioned on top of the cathode. Additional KOH electrolyte solutionwas added to the separator to ensure that electrolyte solution fullypenetrated the separator and wet the underlying cathode. A polymericinsulating seal was placed on the edge of the anode can. About 2.6 g ofanode slurry containing zinc alloy particles, electrolyte solution, anda gelling agent was added to the anode can. Next, the anode can with thepolymeric seal was positioned on top of the cathode can and the two cansmechanically crimped together to hermetically seal the cell.

Generally, cells were tested within 24 hours after closure. OCV valueswere measured immediately before discharge and are listed in Table 3,infra. Cells were discharged continuously at relatively low and highrates of 7.5 mA/g and 60 mA/g, respectively to a cutoff voltage of 0.8V. Gravimetric specific capacities (i.e., mAh/g) for cells discharged atlow and high rates are given in Table 3, infra. The capacity of thecells of Example 2b containing delithiated Li_(0.06)NiO₂ prepared fromthe LiNiO₂ of Example 1 and discharged to a 0.8 V cutoff at a 10 mA/gconstant current is about 150% of that of the cells of ComparativeExample 1 containing EMD (e.g., Tronox AB) as the only cathode activematerial. Further, the discharge voltage profile has two relatively flatplateaus with average voltage values of about 1.55 V and 1.35 V. Arepresentative discharge curve for the cells of Example 2b is shown ascurve c in FIG. 10.

Example 3 Synthesis of Metal-Substituted Lithium Nickel Oxide,LiNi_(1-y-z)Co_(y)M_(z)O₂

Metal-doped Li(Ni_(1-y-z)Co_(y)Al_(z))O₂ andLi(Ni_(1-y-z)Co_(y)Mg_(z))O₂ systems shown in the ternary compositiondiagram in FIG. 2 were synthesized, delithiated, and evaluated forperformance of the corresponding delithiated (i.e., lithium deficient)metal-doped nickel oxide active materials with regard to oxygen gasevolution, initial open circuit voltage (OCV), fresh (i.e., 24 hour)discharge capacity, and capacity retention after storage at ambient andelevated temperatures.

Metal-substituted lithium nickel oxides, LiNi_(1-y-z)Co_(y)M_(z)O₂(M=Mg, Al) were synthesized by blending 10.00 g of spherical β-nickeloxyhydroxide powder prepared by oxidation of a commercial sphericalβ-nickel hydroxide powder (e.g., Changsha Research Institute of Mining &Metallurgy, Changsha, P.R.C; Kansai Catalyst Co., Ltd., Osaka, Japan) bythe method of Comparative Example 2 (infra) with stoichiometric amountsof a cobalt oxide (Co₃O₄, Aldrich, 99.8%) and either magnesium oxide(MgO, Aldrich, >99%) or aluminum metal powder (Al, Acros, 99%) andlithium hydroxide monohydrate (LiOH.H₂O, Aldrich, >99%) to obtain thetarget atom ratios required for the desired compositions. The targetExample 3 compositions have the following Li:Ni:Co:M metal atom ratios:Example 3a 1:0.96:0.04:0; 3b 1:0.92:0.08:0; 3c 1:0.88:0.12:0;3d-1(M=Mg), 3d-2(M=Al) 1:0.98:0:0.2; 3e-1(M=Mg), 3e-2(M=Al)1:0.96:0:0.04; 3f-1(M=Mg), 3f-2(M=Al) 1:0.92:0:0.08; 3g-1(M=Mg),3g-2(M=Al) 1:0.96:0.02:0.02; 3h-1(M=Mg), 3h-2(M=Al) 1:0.92:0.06:0.02;3i-1(M=Mg), 3i-2(M=Al) 1:0.92:0.04:0.04; 3j-1 (M=Mg), 3j-2(M=Al)1:0.92:0.02:0.06; 3k-1(M=Mg), 3k-2(M=Al) 1:0.88:0.10:0.02; 3l-1(M=Mg),31-2(M=Al) 1:0.88:0.08:0.04; 3m-1(M=Mg), 3m-2(M=Al) 1:0.88:0.06:0.06;3n-1(M=Mg), 3n-2(M=Al) 1:0.88:0.04:0.08. All the mixtures weresimultaneously mixed by high-energy milling and heated to 210° C. at aramp rate of 0.5° C./min, held for 16-20 hours at temperature in an O₂gas flow, and allowed to furnace cool. The mixtures were simultaneouslyre-milled and re-heated in an O₂ flow first to 150° C. (2.5° C./min) andheld for 30 minutes, next to 350° C. (4° C./min) and held for 3 hours,and finally to 800° C. (4° C./min) and held for 48 hours and thenallowed to furnace cool to ambient room temperature (in an O₂ flow).

The product powders were re-milled to break up aggregates and the x-raypowder diffraction patterns measured. The overlaid x-ray diffractionpatterns of the powders are shown in FIGS. 3 and 4. The measured x-raydiffraction patterns for the 25 metal-doped and undoped lithium nickeloxides were consistent with that of a layered α-FeO₂-type structure andcomparable to that reported for a stoichiometric LiNiO₂ (ICDD,PDF#09-0063).

Elemental analyses of selected compositions of delithiatedmetal-substituted nickel oxide of Examples 2 and 3 (after acidtreatment) are summarized in Table 1. Samples of metal-substitutedlithium nickel oxides were acid-treated for two different periods oftime (e.g., 20 and 40 hours) to determine the relationship betweentreatment time and the extent of delithiation (i.e., lithiumextraction). All of the samples were treated simultaneously for the samelength of time and under the same temperature and mixing conditions tominimize variability. In general, most of the lithium ions appeared tobe removed during the first 20 hours of acid-treatment, nearlyindependent of the composition. However, removal of any portion of theremaining lithium during an additional 20 hours of acid treatmentsignificantly increased the total discharge capacity. Additional acidtreatment of selected samples of metal-substituted lithium nickel oxidefor up to 60 hours total did not substantially decrease the amount ofresidual Li nor increase discharge capacity in button cells. Residual Lilevels corresponded to an atom ratio of about 0.1 or less (i.e., <1 wt%) for acid treatment times of 40 hours or greater. In contrast, theamount of residual Li level after 20 hours of acid treatment wasgenerally greater than three times that for 40 hours (e.g., >2 wt %).

TABLE 1 Elemental analyses for a selection of layered metal-substitutedlithium nickel oxides and the corresponding delithiated Ni(IV) oxidesand a Ni(OH)₂ precursor. Ex. Nominal Composition Delith. Metal atomratios No. of Precursor Time (h) Li Ni Co Mg Al 2° LiNiO₂ 20 0.31 1.04 —— — 2b LiNiO₂ 40 0.06 1.09 — — — — LiNi_(0.96)Mg_(0.04)O₂ 20 0.19 1.02 —0.04 — 3e-1 LiNi_(0.96)Mg_(0.04)O₂ 40 0.06 1.02 — 0.04 — —LiNi_(0.96)Al_(0.04)O₂ 20 0.30 1.01 — — 0.02 3e-2 LiNi_(0.96)Al_(0.04)O₂40 0.07 1.03 — — 0.03 — LiNi_(0.96)Co_(0.02)Mg_(0.02)O₂ 20 0.20 1.070.05 0.02 — — LiNi_(0.92)Co_(0.04)Mg_(0.04)O₂ 20 0.31 1.00 0.08 0.04 —3i-1 LiNi_(0.92)Co_(0.04)Mg_(0.04)O₂ 40 0.07 1.01 0.10 0.04 — —LiNi_(0.92)Co_(0.04)Al_(0.04)O₂ 20 0.13 0.99 0.08 — 0.04 —LiNi_(0.92)Co_(0.08)O₂ 20 0.33 0.96 0.12 — — 3b LiNi_(0.92)Co_(0.08)O₂40 0.12 1.00 0.13 — — 3m-1 LiNi_(0.88)Co_(0.06)Mg_(0.06)O₂ 40 0.08 1.020.07 0.10 — 3k-1 LiNi_(0.88)Co_(0.10)Mg_(0.02)O₂ 40 0.01 0.96 0.14 0.02— — Ni(OH)₂ — — 0.98 0.02 — —

Samples were measured using inductively coupled plasma atomic emissionspectroscopy (“ICP-AE”) by a commercial analytical laboratory (e.g.,Galbraith Laboratories, Inc., Knoxville, Tenn.). Average particle sizesfor the metal-substituted lithium nickel oxides can be estimated fromanalysis of SEM micrographs. All of the synthesized compositionsexhibited strongly faceted crystallites ranging in size from about 1 to4 microns as shown for several selected samples in FIG. 5. All themetal-substituted lithium nickel oxide samples showed evidence for someinter-crystallite sintering resulting in the formation of largeraggregates composed of lightly sintered crystallites prior todelithiation. Specific surface areas (BET) of these aggregates wererelatively low, generally less than about 1 m²/g.

Example 4 Synthesis of Delithiated Metal-Doped Nickel Oxide,Li_(x)Ni_(1-y-z)Co_(y)M^(a) _(z)O₂

A 10.0 g portion of each of the metal-doped lithium nickel oxidesLiNi_(1-y-z)Co_(y)M^(a) _(z)O₂ (M=Mg, Al) of Examples 3a-n wassimultaneously stirred in separate 150 ml aliquots of 6M H₂SO₄ solutionheld at about 0° C. (e.g., 2-5° C.) for 20 hours and another portion ofeach for 40 hours. The delithiated solids were collected by filtration,washed with deionized water until washings had nominally neutral pH, anddried at 80° C. in air. The delithiated powders of Examples 4a-n havethe following nominal Ni:Co:M metal atom ratios: Example 4a 0.96:0.04:0;4b 0.92:0.08:0; 4c 0.88:0.12:0; 4d-1(M=Mg), 2(M=Al) 0.98:0:0.2;4e-1(M=Mg), 4e-2(M=Al) 0.96:0:0.04; 4f-1(M=Mg), 4f-2(M=Al) 0.92:0:0.08;4g-1(M=Mg), 4g-2(M=Al) 0.96:0.02:0.02; 4h-1(M=Mg), 4h-2(M=Al)0.92:0.06:0.02; 4i-1(M=Mg), 4i-2(M=Al) 0.92:0.04:0.04; 4j-1 (M=Mg),4j-2(M=Al) 0.92:0.02:0.06; 4k-1(M=Mg), 4k-2(M=Al) 0.88:0.10:0.02;4l-1(M=Mg), 4l-2(M=Al) 0.88:0.08:0.04; 4m-1(M=Mg), 4m-2(M=Al)0.88:0.06:0.06; 4n-1(M=Mg), 4n-2(M=Al) 0.88:0.04:0.08. X-ray powderdiffraction patterns of the dried solids were measured using Cu Kαradiation. Thermal stabilities of selected samples of delithiatedpowders of Example 4a-n were determined by DSC. The amount of residuallithium was determined for selected samples of delithiated powders ofExample 4a-n by ICP-EA and is shown in Table 1.

To assess the relative effectiveness of partial substitution of Ni byvarious metal ions on decreasing the extent of electrolyte oxidation bythe delithiated metal-doped nickel (IV) oxides, the amount of evolvedoxygen gas was measured as a function of time. Mixtures containing 60.6wt % delithiated metal-doped nickel(IV) oxide, 3 wt % graphite, and 36.4wt % alkaline electrolyte solution were placed inside laminated foilbags and heat-sealed closed. The bags were placed in an oven and held atvarious temperatures, for example, 25, 45 or 60° C. for pre-determinedperiods of time. The total amount of oxygen gas evolved per gram ofdelithiated nickel (IV) oxide was determined by measuring the relativebuoyancy of the foil bag containing the trapped gas using Archimede'sprinciple after storage for 0.5, 3.5, 7, 14, and 21 days. Severalsamples of delithiated metal-doped nickel(IV) oxides havingrepresentative compositions were evaluated.

Other materials having known gassing properties can be used as controls.For example, a sample of delithiated metal-doped nickel (IV) oxideevolved the largest amount of gas in the shortest period of time. After3.5 days at 25° C., more than 7 cm³ of oxygen gas per gram was evolved.In the same period of time at the same temperature, less than 0.5 cm³ ofoxygen was evolved per gram of a commercial EMD. Further, during thesame period of time (i.e., 3.5 days), a delithiated cobalt-doped nickel(IV) oxide having a nominal composition of Li_(0.12)Ni_(0.92)Co_(0.08)O₂evolved the least amount of gas, about 40% of that evolved by thedelithiated undoped nickel (IV) oxide. In fact, the total amount ofoxygen gas evolved after 21 days at 25° C. was less than 4.25 cm³/gramfor the delithiated cobalt-doped nickel (IV) oxide or less than 50% ofthat evolved by the delithiated undoped nickel (IV) oxide. A delithiatedmagnesium-doped nickel (IV) oxide having the nominal compositionLi_(0.06)Ni_(0.96)Mg_(0.04)O₂ evolved less than 6 cm³/gram after 21days. A delithiated cobalt and magnesium-doped nickel (IV) oxide havingthe nominal composition Li_(0.07)Ni_(0.92)Co_(0.04)Mg_(0.04)O₂ evolvedabout 10% more total oxygen than the magnesium-only doped nickel (IV)oxide. The rate of gas evolution with time also decreased rapidly forthose compositions having the lowest amounts of total evolved oxygen. Itis believed that surface passivation could be responsible for the rapidcessation of oxygen evolution. Oxygen gas evolution test results forselected compositions are summarized in Table 2.

TABLE 2 Oxygen gas evolution at 25° C. by selected delithiatedmetal-doped Ni(IV) oxides Vol. gas evolved/g matl @25° C. (cm³) Ex. 0.53.5 7 14 21 No. Nominal Compositions days days days days days 2bLi_(0.06)NiO₂ 5.8 7.2 7.6 8.4 8.6 4e-1 Li_(0.06)Ni_(0.96)Mg_(0.04)O₂ 2.94.4 5.7 5.8 5.9 4e-2 Li_(0.07)Ni_(0.96)Al_(0.04)O₂ 5.3 6.5 7.2 7.5 8.24i-1 Li_(0.07)Ni_(0.96)Co_(0.04)Mg_(0.04)O₂ 4.1 5.3 5.9 6.2 6.5 4bLi_(0.12)Ni_(0.92)Co_(0.08)O₂ 3.1 3.2 4.1 4.2 4.4 C-2Li_(x)Ni_(0.8)Co_(0.15)Al_(0.05)O₂ — — 2.8 — —

Discharge performance of delithiated metal-doped nickel (IV)-containingoxides acid treated for at least 40 hours was evaluated in 635-typealkaline button cells. Formulation of the cathode mix included blendingthe delithiated metal-doped nickel (IV) oxide with an oxidationresistant graphite (e.g., Timrex SFG-15 from Timcal), and alkalineelectrolyte (9N KOH) in a 75:20:5 mass ratio. The total weight ofcathode mix in each cell was about 0.45 g. The anode contained a largeexcess of Zn slurry (e.g., about 2.6 g/cell). OCV values measuredimmediately after cell closure generally ranged from about 1.84 to 1.92V. Cells were held for at least about 24 hours at ambient temperature(i.e., “fresh”) to ensure thorough absorption of electrolyte by theseparator and cathode. OCV values measured immediately before the startof discharge generally ranged from about 1.72 to 1.81 V. Generally,fresh OCV values appeared to be independent of dopant type and levelexcept for those compositions having high levels of Mg only. Cells weredischarged both at a relative low rate (e.g., about 7.5 mA/g of activematerial) as well as a relative high rate (e.g., about 60 mA/g of activematerial) to a 0.8 V cutoff voltage. Overlays of representative low-ratedischarge curves for button cells with cathodes including selectedcompositions of delithiated metal-doped nickel (IV) oxides having aconstant total dopant concentration are shown in FIGS. 6 and 7. Thelow-rate discharge curves characteristically have a single, relativelyflat voltage plateau ranging between about 1.5 and 1.6 V. Averagedischarge voltage (i.e., CCV at 50% depth of discharge, viz. “50% DOD”)decreased monotonically with increasing cobalt level (i.e., in theabsence of Mg or Al). Highest values of average discharge voltage wereobtained for compositions containing Mg or Al and little or no Co.Post-storage capacity retention was determined for button cellsdischarged at low-rate after holding for 1 week at 25° C. and 45° C.Average discharge capacities, OCV, and average discharge voltages forall 25 compositions of delithiated metal-doped nickel (IV) oxides aresummarized in Table 3.

TABLE 3 Discharge capacities for alkaline button cells with cathodescontaining selected delithiated cobalt/magnesium/aluminum-doped nickel(IV) oxides High rate OCV CCV Low rate capacity capacity Ex. Nominal 24h, 7.5 mA/g (7.5 mA/g) (60 mA/g) No. Compositions 25° C. 50% DOD 24 h,25° C. l wk, 25° C. l wk, 45° C. 24 h, 25° C. 2b NiO₂ 1.84 1.57 334 317277 381 4a Ni_(0.96)Co_(0.04)O₂ 1.78 1.53 364 321 379 4bNi_(0.92)Co_(0.08)O₂ 1.77 1.51 358 333 315 372 4c Ni_(0.88)Co_(0.12)O₂1.79 1.50 337 302 320 4d-1 Ni_(0.98)Mg_(0.02)O₂ 1.81 1.56 359 322 3634e-1 Ni_(0.96)Mg_(0.04)O₂ 1.70 1.57 365 347 307 387 4f-1Ni_(0.92)Mg_(0.08)O₂ 1.61 1.49 190 228 — 4g-1Ni_(0.96)Co_(0.02)Mg_(0.02)O₂ 1.79 1.56 322 287 345 4h-1Ni_(0.92)Co_(0.06)Mg_(0.02)O₂ 1.76 1.54 368 318 287 4i-1Ni_(0.92)Co_(0.04)Mg_(0.04)O₂ 1.71 1.55 373 362 — 387 4j-1Ni_(0.92)Co_(0.02)Mg_(0.06)O₂ 1.72 1.57 369 — 350 4k-1Ni_(0.88)Co_(0.10)Mg_(0.02)O₂ 1.81 1.52 303 265 370 4l-1Ni_(0.88)Co_(0.08)Mg_(0.04)O₂ 1.77 1.55 316 283 332 4m-1Ni_(0.88)Co_(0.06)Mg_(0.06)O₂ 1.78 1.58 347 318 368 4n-1Ni_(0.88)Co_(0.04)Mg_(0.08)O₂ — — — 293 — 4d-2 Ni_(0.98)Al_(0.02)O₂ 1.801.59 352 295 373 4e-2 Ni_(0.96)Al_(0.04)O₂ 1.78 1.59 363 236 323 3744f-2 Ni_(0.92)Al_(0.08)O₂ 1.80 1.57 286 242 383 4g-2Ni_(0.96)Co_(0.02)Al_(0.02)O₂ 1.76 1.56 359 302 373 4h-2Ni_(0.92)Co_(0.06)Al_(0.02)O₂ 1.76 1.53 342 301 328 4i-2Ni_(0.92)Co_(0.04)Al_(0.04)O₂ 1.81 1.56 340 294 340 4j-2Ni_(0.92)Co_(0.02)Al_(0.06)O₂ 1.75 1.57 351 292 383 4k-2Ni_(0.88)Co_(0.10)Al_(0.02)O₂ 1.78 1.52 338 302 355 4l-2Ni_(0.88)Co_(0.08)Al_(0.04)O₂ 1.79 1.54 360 318 374 4m-2Ni_(0.88)Co_(0.06)Al_(0.06)O₂ 1.78 1.55 340 266 333 4n-2Ni_(0.88)Co_(0.04)Al_(0.08)O₂ 1.72 1.57 360 316 338 C-3aNi_(0.9)Co_(0.1)O₂ — — 355 — — C-3b Ni_(0.8)Co_(0.2)O₂ 1.81 1.50 335 — —C-2a Ni_(0.8)Co_(0.15)Al_(0.05)O₂ 1.85 1.55 325 — — C-2bNi_(0.791)Co_(0.149)Al_(0.049)B_(0.01)O₂ 1.83 1.55 335 — —

Button cells having the greatest low-rate (i.e., 7.5 mA/g) freshspecific capacities generally contained delithiated metal-doped nickel(IV) oxides having nickel partially substituted by a combination ofcobalt and magnesium and a total substitution level of less than about10 atom %. The average discharge capacity values generally ranged fromabout 365 to 375 mAh/g and corresponded to about 110-112% of that forcells containing delithiated undoped nickel oxide. Similarly, cellscontaining delithiated singly-doped nickel (IV) oxides in which thenickel ions were partially substituted by only cobalt, magnesium oraluminum ions at a level of less than about 5 atom % had specificcapacities that were up to about 108-109% of that for cells withdelithiated undoped nickel (IV) oxide. Most of the cells containingeither delithiated singly or multiply-doped nickel (IV) oxides hadlow-rate discharge capacities that were either comparable to or slightlygreater (e.g., 5% greater) than control cells containing a delithiatedundoped nickel (IV) oxide. Further, cells containing delithiatedmetal-doped nickel (IV) oxides that had been acid-treated for 40 hoursor greater consistently had >80% higher capacities than cells containingdelithiated metal-doped nickel (IV) oxides acid-treated for only 20hours as shown in FIG. 8.

Button cells containing delithiated metal-doped nickel (IV) oxidesdischarged at a relative high-rate (e.g., 60 mA/g, 100 mA/g) hadspecific capacities that generally were comparable to or even slightlygreater than that of cells containing delithiated doped nickel (IV)oxide. Surprisingly, the high-rate capacities for nearly all the cellscontaining delithiated metal-doped nickel (IV) oxides were comparable to(i.e., 95-101% of the low-rate capacity) or even slightly greater (i.e.,104-114% of the low-rate capacity) than the corresponding low-ratecapacities. For several compositions having relatively high metal dopantlevels of either Mg or Al (e.g., Ni_(0.92)M_(0.08)O₂, M=Mg, Al), thehigh-rate discharge capacities were substantially greater than thecorresponding low-rate capacities. This is consistent with a relativelylow level of cell polarization and excellent high-rate performance forcells containing delithiated metal-doped nickel (IV) oxides.

Post-storage capacity retention was determined for button cellscontaining delithiated metal-doped nickel (IV) oxides discharged atlow-rate after holding for 1 week at 25° C. and 45° C. Average dischargecapacities after storage at 25 and 45° C. as well as the correspondingcalculated percent capacity retentions are summarized in Table 4.Capacities of cells containing delithiated metal-doped nickel (IV)oxides stored at 25° C. for 1 week and then discharged at low rate to a0.8 V cutoff generally ranged from about 85 to 95% of the correspondingfresh capacities (i.e., held for 24 hours at 25° C. before discharge).Capacity retention of cells stored at 45° C. for 1 week ranged fromabout 80% to 90% of the fresh capacities for nearly all the delithiatedmetal-doped nickel (IV) oxides. Capacity retention for cells containingdelithiated undoped nickel (IV) oxide was up to 83%. The highestcapacity retention (≧90%) after storage at 45° C. was obtained for cellscontaining delithiated cobalt and/or magnesium-doped nickel (IV) oxides.

TABLE 4 Discharge capacity retention for alkaline button cells withcathodes containing selected delithiated cobalt/magnesium/aluminum-dopednickel (IV) oxides Low-rate capacity Low-rate Capacity Low-rate CapacityEx. Nominal 24 h capacity retention capacity retention No. Compositions@25° C. 1 wk@25° C. (%) 1 wk@45° C. (%) 2b NiO₂ 334 317 95 278 83 4aNi_(0.96)Co_(0.04)O₂ 364 321 88 4b Ni_(0.92)Co_(0.08)O₂ 358 333 93 31488 4c Ni_(0.88)Co_(0.12)O₂ 337 302 90 4d-1 Ni_(0.98)Mg_(0.02)O₂ 359 32290 4e-1 Ni_(0.96)Mg_(0.04)O₂ 365 347 95 308 84 4f-1 Ni_(0.92)Mg_(0.08)O₂190 228 120 4g-1 Ni_(0.96)Co_(0.02)Mg_(0.02)O₂ 322 287 89 4h-1Ni_(0.92)Co_(0.06)Mg_(0.02)O₂ 368 318 86 4i-1Ni_(0.92)Co_(0.04)Mg_(0.04)O₂ 373 362 97 — — 4j-1Ni_(0.92)Co_(0.02)Mg_(0.06)O₂ 369 — — 4k-1 Ni_(0.88)Co_(0.10)Mg_(0.02)O₂303 265 87 4l-1 Ni_(0.88)Co_(0.08)Mg_(0.04)O₂ 316 283 90 4m-1Ni_(0.88)Co_(0.06)Mg_(0.06)O₂ 347 318 92 4n-1Ni_(0.88)Co_(0.04)Mg_(0.08)O₂ — 293 — 4d-2 Ni_(0.98)Al_(0.02)O₂ 352 29584 4e-2 Ni_(0.96)Al_(0.04)O₂ 363 236 65 324 89 4f-2 Ni_(0.92)Al_(0.08)O₂286 242 85 4g-2 Ni_(0.96)Co_(0.02)Al_(0.02)O₂ 359 302 84 4h-2Ni_(0.92)Co_(0.06)Al_(0.02)O₂ 342 301 88 4i-2Ni_(0.92)Co_(0.04)Al_(0.04)O₂ 340 294 86 4j-2Ni_(0.92)Co_(0.02)Al_(0.06)O₂ 351 292 83 4k-2Ni_(0.88)Co_(0.10)Al_(0.02)O₂ 338 302 89 4l-2Ni_(0.88)Co_(0.08)Al_(0.04)O₂ 360 318 88 4m-2Ni_(0.88)Co_(0.06)Al_(0.06)O₂ 340 266 78 4n-2Ni_(0.88)Co_(0.04)Al_(0.08)O₂ 360 316 88 C-2aNi_(0.8)Co_(0.15)Al_(0.05)O₂ 325 230 70 C-2bNi_(0.791)Co_(0.149)Al_(0.049)B_(0.01)O₂ 335 — —

Cells containing delithiated cobalt and/or aluminum-doped nickel (IV)oxide generally had lower capacity retention than cells containingcobalt- and/or magnesium-doped nickel (IV) oxide for similar totallevels of substitution. No significant relationship between energyretention and OCV for cells held 24 hours at 45° C. was evident as shownin FIG. 9. Nearly all the cells containing delithiated metal-dopednickel (IV) oxides that had been acid-treated for at least 40 hours hada relatively narrow range of OCV values (e.g., 1.84-1.90 V) and hadrelatively high capacity retention values ranging from about 85 to 90%.

Partial substitution of other metal ions for nickel ions in delithiatedlithium nickel oxides having the general formulaLi_(x)Ni_(1-y-z)Co_(y)M^(a) _(z)O₂, where M^(a) is selected frommagnesium, aluminum, calcium, yttrium, manganese and combinations ofthese, can produce a substantial decrease in the amount of oxygenevolved by the delithiated metal-doped nickel (IV) oxide compared to adelithiated undoped nickel (IV) oxide when immersed in alkalineelectrolyte at 25° C. Button cells containing delithiated cobalt andmagnesium-doped nickel (IV) oxides discharged fresh at low-rate can havespecific capacities up to 112% of that for cells containing adelithiated undoped nickel (IV) oxide. Low levels of residual lithium inthe delithiated metal-doped nickel (IV) oxides are desirable. ResidualLi levels corresponding to x<0.1 in the general formula are preferred,while residual Li levels corresponding to x<0.08 are more preferred, andresidual Li levels corresponding to x<0.05 are even more preferred.

Partial substitution of nickel ions by other metal ions also markedlyincreased the post-storage capacity retention for cells containing thedelithiated metal-doped nickel (IV) oxides relative to cells containinga delithiated undoped nickel (IV) oxide. Referring to Table 4, theimprovement in post-storage capacity retention was significant for cellsstored for 1 week at 45° C. than at 25° C. A total metal dopant levelcorresponding to 0.01≦y+z≦0.15, preferably 0.02≦y+z≦0.12 in the generalformula Li_(x)Ni_(1-y-z)Co_(y)M^(a) _(z)O₂ is suitable, and a totalmetal dopant level corresponding to 0.04≦y+z≦0.10 in the general formulaLi_(x)Ni_(1-y-z)Co_(y)M^(a) _(z)O₂ is preferred. Total metal dopantlevels of y+z>0.15 are undesirable because the decreased amount (i.e.,<85%) of electrochemically active nickel (i.e., Ni(IV), Ni(III)) resultsin decreased total specific capacity. Substitution of nickel ions bymagnesium ions is somewhat more effective than aluminum ions atdecreasing amount of oxygen evolution while increasing the specificcapacity and capacity retention, especially when present in combinationwith cobalt ions. However, substitution by cobalt only at relatively lowlevels, for example, y≦0.1, can result in somewhat greater fresh (i.e.,24 hour) capacity than delithiated undoped nickel (IV) oxide. Therefore,partial substitution (i.e., y≦0.1) of nickel by a combination of cobaltand another metal such as magnesium or aluminum is preferred in order tomaximize fresh capacity, minimize oxygen evolution, and also maximizecapacity retention after storage at elevated temperature for cells withcathodes including delithiated nickel (IV)-containing oxides.

Comparative Example 1 Discharge of β-Nickel Oxyhydroxide in AlkalineButton Cells

A sample of spherical cobalt oxyhydroxide-coated β-nickel oxyhydroxidepowder was prepared from a commercial spherical β-nickel hydroxide(e.g., Kansai Catalyst Co., Ltd., Osaka, Japan) as disclosed by thegeneral method disclosed, for example, in U.S. Pat. No. 8,043,748.

A cathode mix was prepared by blending an oxidation-resistant graphiteand an electrolyte solution containing 35.3 wt % KOH and 2 wt % zincoxide with spherical β-nickel oxyhydroxide powder in a weight ratio ofnickel oxyhydroxide:graphite:electrolyte of 75:20:5. Button cells werefabricated by the general method described in Example 2. The cells ofComparative Example 1 were tested within 24 hours after fabrication. OCVmeasured immediately before discharge was 1.72 V. Cells were dischargedat about 10 mA/g constant current corresponding to a nominal C/30 rateto a 0.8 V cutoff voltage. Average discharge capacity for the cells ofComparative Example 1 was about 200 mAh/g.

Comparative Example 2 Synthesis of DelithiatedLi_(x)(Ni_(0.8)Co_(0.15)Al_(0.05))O₂ andLi_(x)(Ni_(0.8)Co_(0.15)Al_(0.05))_(0.99)B_(0.01)O₂

Samples of commercial lithium nickel cobalt aluminum oxide powders (TodaAmerica Inc., Battle Creek, Mich.) having the nominal compositionsLiNi_(0.8)Co_(0.15)Al_(0.05)O₂ andLi(Ni_(0.8)Co_(0.15)Al_(0.05))_(0.99)B_(0.01)O₂ (i.e.,LiNi_(0.792)Co_(0.149)Al_(0.049)B_(0.01)O₂) were delithiated by the acidtreatment process of Example 2 above to form the delithiatedmetal-substituted Ni(IV) oxides of Comparative Examples 2a and 2b,respectively. Button cells were fabricated by the general method ofExample 2. The cells of Comparative Example 2 were tested within 24hours after fabrication. OCV values ranged from about 1.83 to 1.85 V.Cells were discharged at a low rate of about 10 mA/g constant currentcorresponding to a nominal C/30 rate to a 0.8 V cutoff voltage.Discharge curves for cells containing the delithiated cobalt andaluminum-substituted nickel oxides of Comparative Examples 2a and thecobalt, aluminum, and boron-doped nickel oxide of Comparative Example 2bare compared to those for cells containing the delithiated Li_(x)NiO₂ ofExample 2b and a commercial battery-grade EMD in FIG. 10. Averagedischarge capacities for cells containing the delithiatedcobalt/aluminum/boron-doped nickel oxides of Comparative Examples 2a and2b were 325 mAh/g and 335 mAh/g, respectively.

Comparative Example 3 Synthesis of Delithiated Li_(x)Ni_(1-y)Co_(y)O₂(y=0.1, 0.2)

Samples of commercial lithium nickel cobalt oxide powders (e.g., NEICorp., Somerset, N.J.) having nominal chemical compositions ofLiNi_(0.9)Co_(0.2)O₂ and LiNi_(0.8)Co_(0.1)O₂ were delithiated by theacid treatment process of Example 2 above to form the delithiatedmetal-doped nickel(IV) oxides of Comparative Examples 3a and 3b,respectively. Button cells were fabricated by the general method ofExample 2. The cells of Comparative Example 3 were tested within 24hours after fabrication. The OCV value was typically about 1.81 V. Cellswere discharged at a low rate of about 10 mA/g constant currentcorresponding to a nominal C/30 rate to a 0.8 V cutoff voltage. Averagedischarge capacities for cells containing the delithiated cobalt-dopednickel oxides of Comparative Examples 3a and 3b were about 355 mAh/g and335 mAh/g, respectively.

A number of embodiments of the invention have been described.Nevertheless, it will be understood that various modifications may bemade without departing from the spirit and scope of the invention.

For example, a delithiated metal-doped nickel(IV)-containing complexoxide can be used as the active material in the positive electrode of anelectrochemical capacitor (i.e., super-capacitor, ultra-capacitor,pseudo-capacitor). In some embodiments, a delithiated or a partiallydelithiated nickel(IV)-containing complex oxide can function as anoxidation catalyst. For example, the complex oxide can be included inthe cathode of a metal-air battery, for example, a zinc-air cell. Insome embodiments, a delithiated nickel(IV)-containing oxide can functionas an efficient catalyst for breakdown of water to generate molecularoxygen.

In some embodiments, a delithiated metal-doped nickel(IV) oxide canfunction as the cathode active material in a rechargeable alkalimetal-ion battery, a rechargeable alkaline earth metal-ion battery, aprimary alkali metal battery or a primary alkaline earth metal batteryincluding an aqueous, non-aqueous, polymeric or solid electrolyte. Thealkali metal can be selected from Li, Na, K, or a combination thereof.The alkaline earth metal can be selected from Mg, Ca, or a combinationthereof.

Other embodiments are within the scope of the following claims.

What is claimed is:
 1. A battery, comprising: a cathode comprising anoxide having a formula A_(x)Ni_(1-y-z-w)Co_(y)M^(a) _(z) M^(b) _(w)O₂;an anode; a separator between the cathode and the anode; and an alkalineelectrolyte, wherein A is an alkali metal, M^(a) is a metal dopant,M^(b) is a non-metal dopant, 0≦x≦0.2, w is 0, or 0≦w≦0.02 and0.02≦y+z≦0.25.
 2. The battery of claim 1, wherein x is less than 0.1. 3.The battery of claim 1, wherein 0.02≦y≦0.15.
 4. The battery of claim 1,wherein y is
 0. 5. The battery of claim 1, wherein 0.02≦z≦0.08.
 6. Thebattery of claim 1, wherein z is
 0. 7. The battery of claim 1, wherein wis
 0. 8. The battery of claim 1, wherein 0≦w≦0.02
 9. The battery ofclaim 1, wherein the alkali metal is selected from the group consistingof Li, Na, K, Cs, Rb, and any combination thereof.
 10. The battery ofclaim 1, wherein M^(a) is selected from the group consisting of Ca, Mg,Al, Y, Mn, and any combination thereof.
 11. The battery of claim 1,wherein M^(b) is selected from the group consisting of B, Si, Ge, or acombination thereof.
 12. The battery of claim 1, wherein the oxidefurther comprises protons.
 13. The battery of claim 1, wherein the oxidefurther comprises protons at a stoichiometric ratio of between 0.02 and0.2 relative to total nickel and metal dopants.
 14. The battery of claim1, wherein the oxide is selected from the group consisting ofLi_(x)Ni_(1-y)Co_(y)O₂, Li_(x)Ni_(1-z)Ca_(z)O₂,Li_(x)Ni_(1-y-z)Co_(y)Ca_(z)O₂, Li_(x)Ni_(1-z)Mg_(z)O₂,Li_(x)Ni_(1-y-z)Co_(y)Mg_(z)O₂, Li_(x)Ni_(1-z)Al_(z)O₂, andLi_(x)Ni_(1-y-z)Co_(y)Al_(z)O₂, Li_(x)Ni_(1-z)(Mg, Al)_(z)O₂,Li_(x)Ni_(1-y-z)Co_(y)(Mg, Al)_(z)O₂, Li_(x)Ni_(1-z)Y_(z)O₂,Li_(x)Ni_(1-y-z)Co_(y)Y_(z)O₂, Li_(x)Ni_(1-z)Mn_(z)O₂, andLi_(x)Ni_(1-y-z)Co_(y)Mn_(z)O₂.
 15. The battery of claim 1, wherein Nihas an average oxidation state of greater than +3.25.
 16. The battery ofclaim 1, wherein the anode comprises zinc or a zinc alloy.
 17. Thebattery of claim 1, wherein the electrolyte comprises lithium hydroxide,sodium hydroxide, or potassium hydroxide.
 18. The battery of claim 1,wherein the oxide has a low-rate capacity of at least 350 mAh/g afterstoring for 24 hours at 25° C.
 19. The battery of claim 1, wherein theoxide has a low rate capacity of at least 340 mAh/g after storing forone week at 25° C.
 20. The battery of claim 1, wherein the oxide has alow rate capacity of at least 300 mAh/g after storing for one week at45° C.
 21. The battery of claim 1, wherein the battery has a capacityretention of at least 95 percent after storing for one week at 25° C.22. The battery of claim 1, wherein the battery has a capacity retentionof at least 85 percent after storing for one week at 45° C.
 23. Thebattery of claim 1, wherein the oxide has an open circuit voltage offrom 1.75 to 1.85 V.
 24. The battery of claim 1, wherein the oxide hasan oxygen evolution after storing for three weeks at 25° C. of less than4 cm³/g.
 25. A cathode comprising a cathode active material having theformula A_(x)Ni_(1-y-z-w)Co_(y)M^(a) _(z)M^(b) _(w)O₂, wherein A is analkali metal, M^(a) is a metal dopant, M^(b) is a non-metal dopant,0≦x≦0.2, w is 0, or 0≦w≦0.02 and 0.02≦y+z≦0.25.
 26. The cathode of claim25, wherein x is less than 0.1.
 27. The cathode of claim 25, wherein yis 0 or 0.02≦y≦0.15.
 28. The cathode of claim 25, wherein z is 0 or0.02≦z≦0.08.
 29. The cathode of claim 25, wherein the alkali metal isselected from the group consisting of Li, Na, K, Cs, Rb, and anycombination thereof.
 30. The cathode of claim 25, wherein M^(a) isselected from the group consisting of Ca, Mg, Al, Y, Mn, and anycombination thereof.
 31. The cathode of claim 25, wherein M^(b) isselected from the group consisting of B, Si, Ge, or a combinationthereof.
 32. The cathode of claim 25, wherein the oxide furthercomprises protons at a stoichiometric ratio of between 0.02 and 0.2. 33.The cathode of claim 25, wherein the oxide is selected from the groupconsisting of Li_(x)Ni_(1-y)Co_(y)O₂, Li_(x)Ni_(1-z)Ca_(z)O₂,Li_(x)Ni_(1-y-z)Co_(y)Ca_(z)O₂, Li_(x)Ni_(1-z)Mg_(z)O₂,Li_(x)Ni_(1-y-z)Co_(y)Mg_(z)O₂, Li_(x)Ni_(1-z)Al_(z)O₂, andLi_(x)Ni_(1-y-z)Co_(y)Al_(z)O₂, Li_(x)Ni_(1-z)(Mg, Al)_(z)O₂,Li_(x)Ni_(1-y-z)Co_(y)(Mg, Al)_(z)O₂, Li_(x)Ni_(1-z)Y_(z)O₂,Li_(x)Ni_(1-y-z)Co_(y)Y_(z)O₂, Li_(x)Ni_(1-z)Mn_(z)O₂, andLi_(x)Ni_(1-y-z)Co_(y)Mn_(z)O₂.
 34. A battery comprising the cathode ofclaim 25, an anode including zinc or zinc alloy particles, an alkalineelectrolyte solution, and a separator.